[v2,4/7] drm/msm/dpu: allow just single IRQ callback

DPU interrupts code allows multiple callbacks per interrut. In reality
none of the interrupts is shared between blocks (and will probably never
be). Drop support for registering multiple callbacks per interrupt to
simplify interrupt handling code.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

---
 drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h  |  18 +--
 drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c   |   6 +-
 .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h  |   2 +-
 .../drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c  |  10 +-
 .../drm/msm/disp/dpu1/dpu_encoder_phys_vid.c  |   6 +-
 .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 144 +++++++-----------
 .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h |  12 +-
 drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h       |  12 --
 drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h     |  10 +-
 9 files changed, 86 insertions(+), 134 deletions(-)

-- 
2.30.2

On 2021-06-17 15:20, Dmitry Baryshkov wrote:
> DPU interrupts code allows multiple callbacks per interrut. In reality

/interrupt
> none of the interrupts is shared between blocks (and will probably 

> never

> be). Drop support for registering multiple callbacks per interrupt to

> simplify interrupt handling code.

> 

> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>


I need to check on why we had this design originally and we still do.
the idx with which we are registering today can generate only one hw 
interrupt.
But i am not sure if something for planned for future use. Will update 
in a day or two.

meanwhile some comments and questions below.

> ---

>  drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h  |  18 +--

>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c   |   6 +-

>  .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h  |   2 +-

>  .../drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c  |  10 +-

>  .../drm/msm/disp/dpu1/dpu_encoder_phys_vid.c  |   6 +-

>  .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 144 +++++++-----------

>  .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h |  12 +-

>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h       |  12 --

>  drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h     |  10 +-

>  9 files changed, 86 insertions(+), 134 deletions(-)

> 

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h

> index 90ae6c9ccc95..44ab97fb2964 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h

> @@ -46,10 +46,8 @@ u32 dpu_core_irq_read(

>   *                             interrupt

>   * @dpu_kms:		DPU handle

>   * @irq_idx:		irq index

> - * @irq_cb:		IRQ callback structure, containing callback function

> - *			and argument. Passing NULL for irq_cb will unregister

> - *			the callback for the given irq_idx

> - *			This must exist until un-registration.

> + * @irq_cb:		IRQ callback funcion.

> + * @irq_arg:		IRQ callback argument.

>   * @return:		0 for success registering callback, otherwise failure

>   *

>   * This function supports registration of multiple callbacks for each

> interrupt.

> @@ -57,17 +55,16 @@ u32 dpu_core_irq_read(

>  int dpu_core_irq_register_callback(

>  		struct dpu_kms *dpu_kms,

>  		int irq_idx,

> -		struct dpu_irq_callback *irq_cb);

> +		void (*irq_cb)(void *arg, int irq_idx),

> +		void *irq_arg);

> 

>  /**

>   * dpu_core_irq_unregister_callback - For unregistering callback

> function on IRQ

>   *                             interrupt

>   * @dpu_kms:		DPU handle

>   * @irq_idx:		irq index

> - * @irq_cb:		IRQ callback structure, containing callback function

> - *			and argument. Passing NULL for irq_cb will unregister

> - *			the callback for the given irq_idx

> - *			This must match with registration.

> + * @irq_cb:		IRQ callback funcion.

/function
this typo is there in multiple places
> + * @irq_arg:		IRQ callback argument.

>   * @return:		0 for success registering callback, otherwise failure

>   *

>   * This function supports registration of multiple callbacks for each

> interrupt.

> @@ -75,7 +72,8 @@ int dpu_core_irq_register_callback(

>  int dpu_core_irq_unregister_callback(

>  		struct dpu_kms *dpu_kms,

>  		int irq_idx,

> -		struct dpu_irq_callback *irq_cb);

> +		void (*irq_cb)(void *arg, int irq_idx),

> +		void *irq_arg);

> 

>  /**

>   * dpu_debugfs_core_irq_init - register core irq debugfs

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

> index 1c04b7cce43e..d3557b0f4db9 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c

> @@ -310,7 +310,7 @@ int dpu_encoder_helper_wait_for_irq(struct

> dpu_encoder_phys *phys_enc,

>  				      phys_enc->hw_pp->idx - PINGPONG_0,

>  				      atomic_read(wait_info->atomic_cnt));

>  			local_irq_save(flags);

> -			irq->cb.func(phys_enc, irq->irq_idx);

> +			irq->func(phys_enc, irq->irq_idx);

>  			local_irq_restore(flags);

>  			ret = 0;

>  		} else {

> @@ -352,7 +352,7 @@ int dpu_encoder_helper_register_irq(struct

> dpu_encoder_phys *phys_enc,

>  	}

> 

>  	ret = dpu_core_irq_register_callback(phys_enc->dpu_kms, irq->irq_idx,

> -			&irq->cb);

> +			irq->func, phys_enc);

>  	if (ret) {

>  		DPU_ERROR_PHYS(phys_enc,

>  			"failed to register IRQ callback for %s\n",

> @@ -384,7 +384,7 @@ int dpu_encoder_helper_unregister_irq(struct

> dpu_encoder_phys *phys_enc,

>  	}

> 

>  	ret = dpu_core_irq_unregister_callback(phys_enc->dpu_kms, 

> irq->irq_idx,

> -			&irq->cb);

> +			irq->func, phys_enc);

>  	if (ret) {

>  		DRM_ERROR("unreg cb fail id=%u, intr=%d, irq=%d ret=%d",

>  			  DRMID(phys_enc->parent), intr_idx,

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h

> index e7270eb6b84b..80d87871fd94 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h

> @@ -174,7 +174,7 @@ struct dpu_encoder_irq {

>  	const char *name;

>  	enum dpu_intr_idx intr_idx;

>  	int irq_idx;

> -	struct dpu_irq_callback cb;

> +	void (*func)(void *arg, int irq_idx);

>  };

> 

>  /**

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c

> index aa01698d6b25..f921a5c99456 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c

> @@ -782,30 +782,28 @@ struct dpu_encoder_phys 

> *dpu_encoder_phys_cmd_init(

>  	phys_enc->enable_state = DPU_ENC_DISABLED;

>  	for (i = 0; i < INTR_IDX_MAX; i++) {

>  		irq = &phys_enc->irq[i];

> -		INIT_LIST_HEAD(&irq->cb.list);

>  		irq->irq_idx = -EINVAL;

> -		irq->cb.arg = phys_enc;

>  	}

> 

>  	irq = &phys_enc->irq[INTR_IDX_CTL_START];

>  	irq->name = "ctl_start";

>  	irq->intr_idx = INTR_IDX_CTL_START;

> -	irq->cb.func = dpu_encoder_phys_cmd_ctl_start_irq;

> +	irq->func = dpu_encoder_phys_cmd_ctl_start_irq;

> 

>  	irq = &phys_enc->irq[INTR_IDX_PINGPONG];

>  	irq->name = "pp_done";

>  	irq->intr_idx = INTR_IDX_PINGPONG;

> -	irq->cb.func = dpu_encoder_phys_cmd_pp_tx_done_irq;

> +	irq->func = dpu_encoder_phys_cmd_pp_tx_done_irq;

> 

>  	irq = &phys_enc->irq[INTR_IDX_RDPTR];

>  	irq->name = "pp_rd_ptr";

>  	irq->intr_idx = INTR_IDX_RDPTR;

> -	irq->cb.func = dpu_encoder_phys_cmd_pp_rd_ptr_irq;

> +	irq->func = dpu_encoder_phys_cmd_pp_rd_ptr_irq;

> 

>  	irq = &phys_enc->irq[INTR_IDX_UNDERRUN];

>  	irq->name = "underrun";

>  	irq->intr_idx = INTR_IDX_UNDERRUN;

> -	irq->cb.func = dpu_encoder_phys_cmd_underrun_irq;

> +	irq->func = dpu_encoder_phys_cmd_underrun_irq;

> 

>  	atomic_set(&phys_enc->vblank_refcount, 0);

>  	atomic_set(&phys_enc->pending_kickoff_cnt, 0);

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c

> index 185379b18572..437af231d6a4 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c

> @@ -725,20 +725,18 @@ struct dpu_encoder_phys 

> *dpu_encoder_phys_vid_init(

>  	phys_enc->enc_spinlock = p->enc_spinlock;

>  	for (i = 0; i < INTR_IDX_MAX; i++) {

>  		irq = &phys_enc->irq[i];

> -		INIT_LIST_HEAD(&irq->cb.list);

>  		irq->irq_idx = -EINVAL;

> -		irq->cb.arg = phys_enc;

>  	}

> 

>  	irq = &phys_enc->irq[INTR_IDX_VSYNC];

>  	irq->name = "vsync_irq";

>  	irq->intr_idx = INTR_IDX_VSYNC;

> -	irq->cb.func = dpu_encoder_phys_vid_vblank_irq;

> +	irq->func = dpu_encoder_phys_vid_vblank_irq;

> 

>  	irq = &phys_enc->irq[INTR_IDX_UNDERRUN];

>  	irq->name = "underrun";

>  	irq->intr_idx = INTR_IDX_UNDERRUN;

> -	irq->cb.func = dpu_encoder_phys_vid_underrun_irq;

> +	irq->func = dpu_encoder_phys_vid_underrun_irq;

> 

>  	atomic_set(&phys_enc->vblank_refcount, 0);

>  	atomic_set(&phys_enc->pending_kickoff_cnt, 0);

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c

> index d2b6dca487e3..7062e7f0e860 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c

> @@ -127,21 +127,17 @@ static const struct dpu_intr_reg dpu_intr_set[] = 

> {

>   */

>  static void dpu_core_irq_callback_handler(struct dpu_kms *dpu_kms, int 

> irq_idx)

>  {

> -	struct dpu_irq_callback *cb;

> -

>  	VERB("irq_idx=%d\n", irq_idx);

> 

> -	if (list_empty(&dpu_kms->hw_intr->irq_cb_tbl[irq_idx]))

> +	if (!dpu_kms->hw_intr->irq_tbl[irq_idx].cb)

>  		DRM_ERROR("no registered cb, idx:%d\n", irq_idx);

> 

> -	atomic_inc(&dpu_kms->hw_intr->irq_counts[irq_idx]);

> +	atomic_inc(&dpu_kms->hw_intr->irq_tbl[irq_idx].count);

> 

>  	/*

>  	 * Perform registered function callback

>  	 */

> -	list_for_each_entry(cb, &dpu_kms->hw_intr->irq_cb_tbl[irq_idx], list)

> -		if (cb->func)

> -			cb->func(cb->arg, irq_idx);

> +	dpu_kms->hw_intr->irq_tbl[irq_idx].cb(dpu_kms->hw_intr->irq_tbl[irq_idx].arg,

> irq_idx);

>  }

> 

>  irqreturn_t dpu_core_irq(struct dpu_kms *dpu_kms)

> @@ -389,24 +385,18 @@ struct dpu_hw_intr *dpu_hw_intr_init(void __iomem 

> *addr,

>  		struct dpu_mdss_cfg *m)

>  {

>  	struct dpu_hw_intr *intr;

> +	int nirq = MDP_INTR_MAX * 32;

> 

>  	if (!addr || !m)

>  		return ERR_PTR(-EINVAL);

> 

> -	intr = kzalloc(sizeof(*intr), GFP_KERNEL);

> +	intr = kzalloc(struct_size(intr, irq_tbl, nirq), GFP_KERNEL);

>  	if (!intr)

>  		return ERR_PTR(-ENOMEM);

> 

>  	__intr_offset(m, addr, &intr->hw);

> 

> -	intr->total_irqs = ARRAY_SIZE(dpu_intr_set) * 32;

> -

> -	intr->cache_irq_mask = kcalloc(ARRAY_SIZE(dpu_intr_set), sizeof(u32),

> -			GFP_KERNEL);

> -	if (intr->cache_irq_mask == NULL) {

> -		kfree(intr);

> -		return ERR_PTR(-ENOMEM);

> -	}

> +	intr->total_irqs = nirq;

> 

>  	intr->irq_mask = m->mdss_irqs;

> 

> @@ -417,31 +407,19 @@ struct dpu_hw_intr *dpu_hw_intr_init(void __iomem 

> *addr,

> 

>  void dpu_hw_intr_destroy(struct dpu_hw_intr *intr)

>  {

> -	if (intr) {

> -		kfree(intr->cache_irq_mask);

> -

> -		kfree(intr->irq_cb_tbl);

> -		kfree(intr->irq_counts);

> -

> +	if (intr)

>  		kfree(intr);

> -	}

>  }

> 

>  int dpu_core_irq_register_callback(struct dpu_kms *dpu_kms, int 

> irq_idx,

> -		struct dpu_irq_callback *register_irq_cb)

> +		void (*irq_cb)(void *arg, int irq_idx),

> +		void *irq_arg)

>  {

>  	unsigned long irq_flags;

> +	int ret;

> 

> -	if (!dpu_kms->hw_intr->irq_cb_tbl) {

> -		DPU_ERROR("invalid params\n");

> -		return -EINVAL;

> -	}

> -

> -	if (!register_irq_cb || !register_irq_cb->func) {

> -		DPU_ERROR("invalid irq_cb:%d func:%d\n",

> -				register_irq_cb != NULL,

> -				register_irq_cb ?

> -					register_irq_cb->func != NULL : -1);

> +	if (!irq_cb) {

> +		DPU_ERROR("invalid ird_idx:%d irq_cb:%ps\n", irq_idx, irq_cb);

>  		return -EINVAL;

>  	}

> 

> @@ -453,39 +431,37 @@ int dpu_core_irq_register_callback(struct

> dpu_kms *dpu_kms, int irq_idx,

>  	VERB("[%pS] irq_idx=%d\n", __builtin_return_address(0), irq_idx);

> 

>  	spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);

> -	trace_dpu_core_irq_register_callback(irq_idx, register_irq_cb);

> -	list_del_init(&register_irq_cb->list);

> -	list_add_tail(&register_irq_cb->list,

> -			&dpu_kms->hw_intr->irq_cb_tbl[irq_idx]);

> -	if (list_is_first(&register_irq_cb->list,

> -			&dpu_kms->hw_intr->irq_cb_tbl[irq_idx])) {

> -		int ret = dpu_hw_intr_enable_irq_locked(

> +

> +	if (dpu_kms->hw_intr->irq_tbl[irq_idx].cb) {

> +		spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);

> +

> +		return -EBUSY;

> +	}

Why is this check present? Ideally there should be only one callback 
registered.
> +

> +	trace_dpu_core_irq_register_callback(irq_idx, irq_cb);

> +	dpu_kms->hw_intr->irq_tbl[irq_idx].arg = irq_arg;

> +	dpu_kms->hw_intr->irq_tbl[irq_idx].cb = irq_cb;

> +

> +	ret = dpu_hw_intr_enable_irq_locked(

>  				dpu_kms->hw_intr,

>  				irq_idx);

> -		if (ret)

> -			DPU_ERROR("Fail to enable IRQ for irq_idx:%d\n",

> +	if (ret)

> +		DPU_ERROR("Fail to enable IRQ for irq_idx:%d\n",

>  					irq_idx);

> -	}

>  	spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);

> 

>  	return 0;

>  }

> 

>  int dpu_core_irq_unregister_callback(struct dpu_kms *dpu_kms, int 

> irq_idx,

> -		struct dpu_irq_callback *register_irq_cb)

> +		void (*irq_cb)(void *arg, int irq_idx),

> +		void *irq_arg)

>  {

>  	unsigned long irq_flags;

> +	int ret;

> 

> -	if (!dpu_kms->hw_intr->irq_cb_tbl) {

> -		DPU_ERROR("invalid params\n");

> -		return -EINVAL;

> -	}

> -

> -	if (!register_irq_cb || !register_irq_cb->func) {

> -		DPU_ERROR("invalid irq_cb:%d func:%d\n",

> -				register_irq_cb != NULL,

> -				register_irq_cb ?

> -					register_irq_cb->func != NULL : -1);

> +	if (!irq_cb) {

> +		DPU_ERROR("invalid ird_idx:%d irq_cb:%ps\n", irq_idx, irq_cb);

>  		return -EINVAL;

>  	}

> 

> @@ -497,18 +473,23 @@ int dpu_core_irq_unregister_callback(struct

> dpu_kms *dpu_kms, int irq_idx,

>  	VERB("[%pS] irq_idx=%d\n", __builtin_return_address(0), irq_idx);

> 

>  	spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);

> -	trace_dpu_core_irq_unregister_callback(irq_idx, register_irq_cb);

> -	list_del_init(&register_irq_cb->list);

> -	/* empty callback list but interrupt is still enabled */

> -	if (list_empty(&dpu_kms->hw_intr->irq_cb_tbl[irq_idx])) {

> -		int ret = dpu_hw_intr_disable_irq_locked(

> -				dpu_kms->hw_intr,

> -				irq_idx);

> -		if (ret)

> -			DPU_ERROR("Fail to disable IRQ for irq_idx:%d\n",

> -					irq_idx);

> -		VERB("irq_idx=%d ret=%d\n", irq_idx, ret);

> +	trace_dpu_core_irq_unregister_callback(irq_idx, irq_cb);

> +

> +	if (WARN_ON(dpu_kms->hw_intr->irq_tbl[irq_idx].cb != irq_cb ||

> +		    dpu_kms->hw_intr->irq_tbl[irq_idx].arg != irq_arg)) {

> +		spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);

> +

> +		return -EINVAL;

>  	}


Why do we need this check too? Any condition where this wont match?

> +

> +	ret = dpu_hw_intr_disable_irq_locked(dpu_kms->hw_intr, irq_idx);

> +	if (ret)

> +		DPU_ERROR("Fail to disable IRQ for irq_idx:%d: %d\n",

> +					irq_idx, ret);

> +

> +	dpu_kms->hw_intr->irq_tbl[irq_idx].cb = NULL;

> +	dpu_kms->hw_intr->irq_tbl[irq_idx].arg = NULL;

> +

>  	spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);

> 

>  	return 0;

> @@ -518,24 +499,18 @@ int dpu_core_irq_unregister_callback(struct

> dpu_kms *dpu_kms, int irq_idx,

>  static int dpu_debugfs_core_irq_show(struct seq_file *s, void *v)

>  {

>  	struct dpu_kms *dpu_kms = s->private;

> -	struct dpu_irq_callback *cb;

>  	unsigned long irq_flags;

> -	int i, irq_count, cb_count;

> -

> -	if (WARN_ON(!dpu_kms->hw_intr->irq_cb_tbl))

> -		return 0;

> +	int i, irq_count;

> +	void *cb;

> 

>  	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++) {

>  		spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);

> -		cb_count = 0;

> -		irq_count = atomic_read(&dpu_kms->hw_intr->irq_counts[i]);

> -		list_for_each_entry(cb, &dpu_kms->hw_intr->irq_cb_tbl[i], list)

> -			cb_count++;

> +		irq_count = atomic_read(&dpu_kms->hw_intr->irq_tbl[i].count);

> +		cb = dpu_kms->hw_intr->irq_tbl[i].cb;

>  		spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);

> 

> -		if (irq_count || cb_count)

> -			seq_printf(s, "idx:%d irq:%d cb:%d\n",

> -					i, irq_count, cb_count);

> +		if (irq_count || cb)

> +			seq_printf(s, "idx:%d irq:%d cb:%ps\n", i, irq_count, cb);

>  	}

> 

>  	return 0;

> @@ -560,15 +535,8 @@ void dpu_core_irq_preinstall(struct dpu_kms 

> *dpu_kms)

>  	dpu_disable_all_irqs(dpu_kms);

>  	pm_runtime_put_sync(&dpu_kms->pdev->dev);

> 

> -	/* Create irq callbacks for all possible irq_idx */

> -	dpu_kms->hw_intr->irq_cb_tbl = kcalloc(dpu_kms->hw_intr->total_irqs,

> -			sizeof(struct list_head), GFP_KERNEL);

> -	dpu_kms->hw_intr->irq_counts = kcalloc(dpu_kms->hw_intr->total_irqs,

> -			sizeof(atomic_t), GFP_KERNEL);

> -	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++) {

> -		INIT_LIST_HEAD(&dpu_kms->hw_intr->irq_cb_tbl[i]);

> -		atomic_set(&dpu_kms->hw_intr->irq_counts[i], 0);

> -	}

> +	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++)

> +		atomic_set(&dpu_kms->hw_intr->irq_tbl[i].count, 0);

>  }

> 

>  void dpu_core_irq_uninstall(struct dpu_kms *dpu_kms)

> @@ -577,7 +545,7 @@ void dpu_core_irq_uninstall(struct dpu_kms 

> *dpu_kms)

> 

>  	pm_runtime_get_sync(&dpu_kms->pdev->dev);

>  	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++)

> -		if (!list_empty(&dpu_kms->hw_intr->irq_cb_tbl[i]))

> +		if (dpu_kms->hw_intr->irq_tbl[i].cb)

>  			DPU_ERROR("irq_idx=%d still enabled/registered\n", i);

> 

>  	dpu_clear_irqs(dpu_kms);

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h

> index d50e78c9f148..9855e176b173 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h

> @@ -40,19 +40,21 @@ enum dpu_hw_intr_reg {

>   * @save_irq_status:  array of IRQ status reg storage created during 

> init

>   * @total_irqs: total number of irq_idx mapped in the hw_interrupts

>   * @irq_lock:         spinlock for accessing IRQ resources

> - * @irq_cb_tbl:       array of IRQ callbacks lists

> - * @irq_counts:       array of IRQ counts

> + * @irq_cb_tbl:       array of IRQ callbacks

>   */

>  struct dpu_hw_intr {

>  	struct dpu_hw_blk_reg_map hw;

> -	u32 *cache_irq_mask;

> +	u32 cache_irq_mask[MDP_INTR_MAX];

>  	u32 *save_irq_status;

>  	u32 total_irqs;

>  	spinlock_t irq_lock;

>  	unsigned long irq_mask;

> 

> -	struct list_head *irq_cb_tbl;

> -	atomic_t *irq_counts;

> +	struct {

> +		void (*cb)(void *arg, int irq_idx);

> +		void *arg;

> +		atomic_t count;

> +	} irq_tbl[];

>  };

> 

>  /**

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h

> index 775bcbda860f..d24dcd852d2e 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h

> @@ -66,18 +66,6 @@

> 

>  #define DPU_NAME_SIZE  12

> 

> -/*

> - * struct dpu_irq_callback - IRQ callback handlers

> - * @list: list to callback

> - * @func: intr handler

> - * @arg: argument for the handler

> - */

> -struct dpu_irq_callback {

> -	struct list_head list;

> -	void (*func)(void *arg, int irq_idx);

> -	void *arg;

> -};

> -

>  struct dpu_kms {

>  	struct msm_kms base;

>  	struct drm_device *dev;

> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h

> b/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h

> index 37bba57675a8..1e2619556f93 100644

> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h

> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h

> @@ -876,25 +876,25 @@ TRACE_EVENT(dpu_pp_connect_ext_te,

>  );

> 

>  DECLARE_EVENT_CLASS(dpu_core_irq_callback_template,

> -	TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),

> +	TP_PROTO(int irq_idx, void *callback),

>  	TP_ARGS(irq_idx, callback),

>  	TP_STRUCT__entry(

>  		__field(	int,				irq_idx	)

> -		__field(	struct dpu_irq_callback *,	callback)

> +		__field(	void *,				callback)

>  	),

>  	TP_fast_assign(

>  		__entry->irq_idx = irq_idx;

>  		__entry->callback = callback;

>  	),

> -	TP_printk("irq_idx:%d callback:%pK", __entry->irq_idx,

> +	TP_printk("irq_idx:%d callback:%ps", __entry->irq_idx,

>  		  __entry->callback)

>  );

>  DEFINE_EVENT(dpu_core_irq_callback_template, 

> dpu_core_irq_register_callback,

> -	TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),

> +	TP_PROTO(int irq_idx, void *callback),

>  	TP_ARGS(irq_idx, callback)

>  );

>  DEFINE_EVENT(dpu_core_irq_callback_template, 

> dpu_core_irq_unregister_callback,

> -	TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),

> +	TP_PROTO(int irq_idx, void *callback),

>  	TP_ARGS(irq_idx, callback)

>  );

<replying from my older email as i couldnt find this thread on my new 
one>

On 2021-08-17 20:30, abhinavk@codeaurora.org wrote:
> On 2021-06-17 15:20, Dmitry Baryshkov wrote:
>> DPU interrupts code allows multiple callbacks per interrut. In reality
> /interrupt
>> none of the interrupts is shared between blocks (and will probably 
>> never
>> be). Drop support for registering multiple callbacks per interrupt to
>> simplify interrupt handling code.
>> 
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> 
> I need to check on why we had this design originally and we still do.
> the idx with which we are registering today can generate only one hw 
> interrupt.
> But i am not sure if something for planned for future use. Will update
> in a day or two.
> 
> meanwhile some comments and questions below.

I did check internally on the original design of this and yes the plan 
was for other
sub-modules to register for callbacks and that callback goes into the 
callback list.

For example, lets say for some reason some other modules like the DSI 
want to register
for the VSYNC interrupt, it can register for a callback and that will 
get added to the
callback list.

But, this never got used that way and even now there is only one 
callback per interrupt.
We dont have a concrete use-case where we will need this in the future 
but like many other things,
we cannot tell for certain.

Since there is no concrete use-case where we might need this, if you 
would like to go ahead
with this, please do.

Once you address the other comments on this, I can ack this.

> 
>> ---
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h  |  18 +--
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c   |   6 +-
>>  .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h  |   2 +-
>>  .../drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c  |  10 +-
>>  .../drm/msm/disp/dpu1/dpu_encoder_phys_vid.c  |   6 +-
>>  .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 144 
>> +++++++-----------
>>  .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h |  12 +-
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h       |  12 --
>>  drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h     |  10 +-
>>  9 files changed, 86 insertions(+), 134 deletions(-)
>> 
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>> index 90ae6c9ccc95..44ab97fb2964 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>> @@ -46,10 +46,8 @@ u32 dpu_core_irq_read(
>>   *                             interrupt
>>   * @dpu_kms:		DPU handle
>>   * @irq_idx:		irq index
>> - * @irq_cb:		IRQ callback structure, containing callback function
>> - *			and argument. Passing NULL for irq_cb will unregister
>> - *			the callback for the given irq_idx
>> - *			This must exist until un-registration.
>> + * @irq_cb:		IRQ callback funcion.
>> + * @irq_arg:		IRQ callback argument.
>>   * @return:		0 for success registering callback, otherwise failure
>>   *
>>   * This function supports registration of multiple callbacks for each
>> interrupt.
>> @@ -57,17 +55,16 @@ u32 dpu_core_irq_read(
>>  int dpu_core_irq_register_callback(
>>  		struct dpu_kms *dpu_kms,
>>  		int irq_idx,
>> -		struct dpu_irq_callback *irq_cb);
>> +		void (*irq_cb)(void *arg, int irq_idx),
>> +		void *irq_arg);
>> 
>>  /**
>>   * dpu_core_irq_unregister_callback - For unregistering callback
>> function on IRQ
>>   *                             interrupt
>>   * @dpu_kms:		DPU handle
>>   * @irq_idx:		irq index
>> - * @irq_cb:		IRQ callback structure, containing callback function
>> - *			and argument. Passing NULL for irq_cb will unregister
>> - *			the callback for the given irq_idx
>> - *			This must match with registration.
>> + * @irq_cb:		IRQ callback funcion.
> /function
> this typo is there in multiple places
>> + * @irq_arg:		IRQ callback argument.
>>   * @return:		0 for success registering callback, otherwise failure
>>   *
>>   * This function supports registration of multiple callbacks for each
>> interrupt.
>> @@ -75,7 +72,8 @@ int dpu_core_irq_register_callback(
>>  int dpu_core_irq_unregister_callback(
>>  		struct dpu_kms *dpu_kms,
>>  		int irq_idx,
>> -		struct dpu_irq_callback *irq_cb);
>> +		void (*irq_cb)(void *arg, int irq_idx),
>> +		void *irq_arg);
>> 
>>  /**
>>   * dpu_debugfs_core_irq_init - register core irq debugfs
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> index 1c04b7cce43e..d3557b0f4db9 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> @@ -310,7 +310,7 @@ int dpu_encoder_helper_wait_for_irq(struct
>> dpu_encoder_phys *phys_enc,
>>  				      phys_enc->hw_pp->idx - PINGPONG_0,
>>  				      atomic_read(wait_info->atomic_cnt));
>>  			local_irq_save(flags);
>> -			irq->cb.func(phys_enc, irq->irq_idx);
>> +			irq->func(phys_enc, irq->irq_idx);
>>  			local_irq_restore(flags);
>>  			ret = 0;
>>  		} else {
>> @@ -352,7 +352,7 @@ int dpu_encoder_helper_register_irq(struct
>> dpu_encoder_phys *phys_enc,
>>  	}
>> 
>>  	ret = dpu_core_irq_register_callback(phys_enc->dpu_kms, 
>> irq->irq_idx,
>> -			&irq->cb);
>> +			irq->func, phys_enc);
>>  	if (ret) {
>>  		DPU_ERROR_PHYS(phys_enc,
>>  			"failed to register IRQ callback for %s\n",
>> @@ -384,7 +384,7 @@ int dpu_encoder_helper_unregister_irq(struct
>> dpu_encoder_phys *phys_enc,
>>  	}
>> 
>>  	ret = dpu_core_irq_unregister_callback(phys_enc->dpu_kms, 
>> irq->irq_idx,
>> -			&irq->cb);
>> +			irq->func, phys_enc);
>>  	if (ret) {
>>  		DRM_ERROR("unreg cb fail id=%u, intr=%d, irq=%d ret=%d",
>>  			  DRMID(phys_enc->parent), intr_idx,
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>> index e7270eb6b84b..80d87871fd94 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>> @@ -174,7 +174,7 @@ struct dpu_encoder_irq {
>>  	const char *name;
>>  	enum dpu_intr_idx intr_idx;
>>  	int irq_idx;
>> -	struct dpu_irq_callback cb;
>> +	void (*func)(void *arg, int irq_idx);
>>  };
>> 
>>  /**
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> index aa01698d6b25..f921a5c99456 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> @@ -782,30 +782,28 @@ struct dpu_encoder_phys 
>> *dpu_encoder_phys_cmd_init(
>>  	phys_enc->enable_state = DPU_ENC_DISABLED;
>>  	for (i = 0; i < INTR_IDX_MAX; i++) {
>>  		irq = &phys_enc->irq[i];
>> -		INIT_LIST_HEAD(&irq->cb.list);
>>  		irq->irq_idx = -EINVAL;
>> -		irq->cb.arg = phys_enc;
>>  	}
>> 
>>  	irq = &phys_enc->irq[INTR_IDX_CTL_START];
>>  	irq->name = "ctl_start";
>>  	irq->intr_idx = INTR_IDX_CTL_START;
>> -	irq->cb.func = dpu_encoder_phys_cmd_ctl_start_irq;
>> +	irq->func = dpu_encoder_phys_cmd_ctl_start_irq;
>> 
>>  	irq = &phys_enc->irq[INTR_IDX_PINGPONG];
>>  	irq->name = "pp_done";
>>  	irq->intr_idx = INTR_IDX_PINGPONG;
>> -	irq->cb.func = dpu_encoder_phys_cmd_pp_tx_done_irq;
>> +	irq->func = dpu_encoder_phys_cmd_pp_tx_done_irq;
>> 
>>  	irq = &phys_enc->irq[INTR_IDX_RDPTR];
>>  	irq->name = "pp_rd_ptr";
>>  	irq->intr_idx = INTR_IDX_RDPTR;
>> -	irq->cb.func = dpu_encoder_phys_cmd_pp_rd_ptr_irq;
>> +	irq->func = dpu_encoder_phys_cmd_pp_rd_ptr_irq;
>> 
>>  	irq = &phys_enc->irq[INTR_IDX_UNDERRUN];
>>  	irq->name = "underrun";
>>  	irq->intr_idx = INTR_IDX_UNDERRUN;
>> -	irq->cb.func = dpu_encoder_phys_cmd_underrun_irq;
>> +	irq->func = dpu_encoder_phys_cmd_underrun_irq;
>> 
>>  	atomic_set(&phys_enc->vblank_refcount, 0);
>>  	atomic_set(&phys_enc->pending_kickoff_cnt, 0);
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>> index 185379b18572..437af231d6a4 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>> @@ -725,20 +725,18 @@ struct dpu_encoder_phys 
>> *dpu_encoder_phys_vid_init(
>>  	phys_enc->enc_spinlock = p->enc_spinlock;
>>  	for (i = 0; i < INTR_IDX_MAX; i++) {
>>  		irq = &phys_enc->irq[i];
>> -		INIT_LIST_HEAD(&irq->cb.list);
>>  		irq->irq_idx = -EINVAL;
>> -		irq->cb.arg = phys_enc;
>>  	}
>> 
>>  	irq = &phys_enc->irq[INTR_IDX_VSYNC];
>>  	irq->name = "vsync_irq";
>>  	irq->intr_idx = INTR_IDX_VSYNC;
>> -	irq->cb.func = dpu_encoder_phys_vid_vblank_irq;
>> +	irq->func = dpu_encoder_phys_vid_vblank_irq;
>> 
>>  	irq = &phys_enc->irq[INTR_IDX_UNDERRUN];
>>  	irq->name = "underrun";
>>  	irq->intr_idx = INTR_IDX_UNDERRUN;
>> -	irq->cb.func = dpu_encoder_phys_vid_underrun_irq;
>> +	irq->func = dpu_encoder_phys_vid_underrun_irq;
>> 
>>  	atomic_set(&phys_enc->vblank_refcount, 0);
>>  	atomic_set(&phys_enc->pending_kickoff_cnt, 0);
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> index d2b6dca487e3..7062e7f0e860 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> @@ -127,21 +127,17 @@ static const struct dpu_intr_reg dpu_intr_set[] 
>> = {
>>   */
>>  static void dpu_core_irq_callback_handler(struct dpu_kms *dpu_kms, 
>> int irq_idx)
>>  {
>> -	struct dpu_irq_callback *cb;
>> -
>>  	VERB("irq_idx=%d\n", irq_idx);
>> 
>> -	if (list_empty(&dpu_kms->hw_intr->irq_cb_tbl[irq_idx]))
>> +	if (!dpu_kms->hw_intr->irq_tbl[irq_idx].cb)
>>  		DRM_ERROR("no registered cb, idx:%d\n", irq_idx);
>> 
>> -	atomic_inc(&dpu_kms->hw_intr->irq_counts[irq_idx]);
>> +	atomic_inc(&dpu_kms->hw_intr->irq_tbl[irq_idx].count);
>> 
>>  	/*
>>  	 * Perform registered function callback
>>  	 */
>> -	list_for_each_entry(cb, &dpu_kms->hw_intr->irq_cb_tbl[irq_idx], 
>> list)
>> -		if (cb->func)
>> -			cb->func(cb->arg, irq_idx);
>> +	dpu_kms->hw_intr->irq_tbl[irq_idx].cb(dpu_kms->hw_intr->irq_tbl[irq_idx].arg,
>> irq_idx);
>>  }
>> 
>>  irqreturn_t dpu_core_irq(struct dpu_kms *dpu_kms)
>> @@ -389,24 +385,18 @@ struct dpu_hw_intr *dpu_hw_intr_init(void 
>> __iomem *addr,
>>  		struct dpu_mdss_cfg *m)
>>  {
>>  	struct dpu_hw_intr *intr;
>> +	int nirq = MDP_INTR_MAX * 32;
>> 
>>  	if (!addr || !m)
>>  		return ERR_PTR(-EINVAL);
>> 
>> -	intr = kzalloc(sizeof(*intr), GFP_KERNEL);
>> +	intr = kzalloc(struct_size(intr, irq_tbl, nirq), GFP_KERNEL);
>>  	if (!intr)
>>  		return ERR_PTR(-ENOMEM);
>> 
>>  	__intr_offset(m, addr, &intr->hw);
>> 
>> -	intr->total_irqs = ARRAY_SIZE(dpu_intr_set) * 32;
>> -
>> -	intr->cache_irq_mask = kcalloc(ARRAY_SIZE(dpu_intr_set), 
>> sizeof(u32),
>> -			GFP_KERNEL);
>> -	if (intr->cache_irq_mask == NULL) {
>> -		kfree(intr);
>> -		return ERR_PTR(-ENOMEM);
>> -	}
>> +	intr->total_irqs = nirq;
>> 
>>  	intr->irq_mask = m->mdss_irqs;
>> 
>> @@ -417,31 +407,19 @@ struct dpu_hw_intr *dpu_hw_intr_init(void 
>> __iomem *addr,
>> 
>>  void dpu_hw_intr_destroy(struct dpu_hw_intr *intr)
>>  {
>> -	if (intr) {
>> -		kfree(intr->cache_irq_mask);
>> -
>> -		kfree(intr->irq_cb_tbl);
>> -		kfree(intr->irq_counts);
>> -
>> +	if (intr)
>>  		kfree(intr);
>> -	}
>>  }
>> 
>>  int dpu_core_irq_register_callback(struct dpu_kms *dpu_kms, int 
>> irq_idx,
>> -		struct dpu_irq_callback *register_irq_cb)
>> +		void (*irq_cb)(void *arg, int irq_idx),
>> +		void *irq_arg)
>>  {
>>  	unsigned long irq_flags;
>> +	int ret;
>> 
>> -	if (!dpu_kms->hw_intr->irq_cb_tbl) {
>> -		DPU_ERROR("invalid params\n");
>> -		return -EINVAL;
>> -	}
>> -
>> -	if (!register_irq_cb || !register_irq_cb->func) {
>> -		DPU_ERROR("invalid irq_cb:%d func:%d\n",
>> -				register_irq_cb != NULL,
>> -				register_irq_cb ?
>> -					register_irq_cb->func != NULL : -1);
>> +	if (!irq_cb) {
>> +		DPU_ERROR("invalid ird_idx:%d irq_cb:%ps\n", irq_idx, irq_cb);
>>  		return -EINVAL;
>>  	}
>> 
>> @@ -453,39 +431,37 @@ int dpu_core_irq_register_callback(struct
>> dpu_kms *dpu_kms, int irq_idx,
>>  	VERB("[%pS] irq_idx=%d\n", __builtin_return_address(0), irq_idx);
>> 
>>  	spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> -	trace_dpu_core_irq_register_callback(irq_idx, register_irq_cb);
>> -	list_del_init(&register_irq_cb->list);
>> -	list_add_tail(&register_irq_cb->list,
>> -			&dpu_kms->hw_intr->irq_cb_tbl[irq_idx]);
>> -	if (list_is_first(&register_irq_cb->list,
>> -			&dpu_kms->hw_intr->irq_cb_tbl[irq_idx])) {
>> -		int ret = dpu_hw_intr_enable_irq_locked(
>> +
>> +	if (dpu_kms->hw_intr->irq_tbl[irq_idx].cb) {
>> +		spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> +
>> +		return -EBUSY;
>> +	}
> Why is this check present? Ideally there should be only one callback 
> registered.
>> +
>> +	trace_dpu_core_irq_register_callback(irq_idx, irq_cb);
>> +	dpu_kms->hw_intr->irq_tbl[irq_idx].arg = irq_arg;
>> +	dpu_kms->hw_intr->irq_tbl[irq_idx].cb = irq_cb;
>> +
>> +	ret = dpu_hw_intr_enable_irq_locked(
>>  				dpu_kms->hw_intr,
>>  				irq_idx);
>> -		if (ret)
>> -			DPU_ERROR("Fail to enable IRQ for irq_idx:%d\n",
>> +	if (ret)
>> +		DPU_ERROR("Fail to enable IRQ for irq_idx:%d\n",
>>  					irq_idx);
>> -	}
>>  	spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> 
>>  	return 0;
>>  }
>> 
>>  int dpu_core_irq_unregister_callback(struct dpu_kms *dpu_kms, int 
>> irq_idx,
>> -		struct dpu_irq_callback *register_irq_cb)
>> +		void (*irq_cb)(void *arg, int irq_idx),
>> +		void *irq_arg)
>>  {
>>  	unsigned long irq_flags;
>> +	int ret;
>> 
>> -	if (!dpu_kms->hw_intr->irq_cb_tbl) {
>> -		DPU_ERROR("invalid params\n");
>> -		return -EINVAL;
>> -	}
>> -
>> -	if (!register_irq_cb || !register_irq_cb->func) {
>> -		DPU_ERROR("invalid irq_cb:%d func:%d\n",
>> -				register_irq_cb != NULL,
>> -				register_irq_cb ?
>> -					register_irq_cb->func != NULL : -1);
>> +	if (!irq_cb) {
>> +		DPU_ERROR("invalid ird_idx:%d irq_cb:%ps\n", irq_idx, irq_cb);
>>  		return -EINVAL;
>>  	}
>> 
>> @@ -497,18 +473,23 @@ int dpu_core_irq_unregister_callback(struct
>> dpu_kms *dpu_kms, int irq_idx,
>>  	VERB("[%pS] irq_idx=%d\n", __builtin_return_address(0), irq_idx);
>> 
>>  	spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> -	trace_dpu_core_irq_unregister_callback(irq_idx, register_irq_cb);
>> -	list_del_init(&register_irq_cb->list);
>> -	/* empty callback list but interrupt is still enabled */
>> -	if (list_empty(&dpu_kms->hw_intr->irq_cb_tbl[irq_idx])) {
>> -		int ret = dpu_hw_intr_disable_irq_locked(
>> -				dpu_kms->hw_intr,
>> -				irq_idx);
>> -		if (ret)
>> -			DPU_ERROR("Fail to disable IRQ for irq_idx:%d\n",
>> -					irq_idx);
>> -		VERB("irq_idx=%d ret=%d\n", irq_idx, ret);
>> +	trace_dpu_core_irq_unregister_callback(irq_idx, irq_cb);
>> +
>> +	if (WARN_ON(dpu_kms->hw_intr->irq_tbl[irq_idx].cb != irq_cb ||
>> +		    dpu_kms->hw_intr->irq_tbl[irq_idx].arg != irq_arg)) {
>> +		spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> +
>> +		return -EINVAL;
>>  	}
> 
> Why do we need this check too? Any condition where this wont match?
> 
>> +
>> +	ret = dpu_hw_intr_disable_irq_locked(dpu_kms->hw_intr, irq_idx);
>> +	if (ret)
>> +		DPU_ERROR("Fail to disable IRQ for irq_idx:%d: %d\n",
>> +					irq_idx, ret);
>> +
>> +	dpu_kms->hw_intr->irq_tbl[irq_idx].cb = NULL;
>> +	dpu_kms->hw_intr->irq_tbl[irq_idx].arg = NULL;
>> +
>>  	spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> 
>>  	return 0;
>> @@ -518,24 +499,18 @@ int dpu_core_irq_unregister_callback(struct
>> dpu_kms *dpu_kms, int irq_idx,
>>  static int dpu_debugfs_core_irq_show(struct seq_file *s, void *v)
>>  {
>>  	struct dpu_kms *dpu_kms = s->private;
>> -	struct dpu_irq_callback *cb;
>>  	unsigned long irq_flags;
>> -	int i, irq_count, cb_count;
>> -
>> -	if (WARN_ON(!dpu_kms->hw_intr->irq_cb_tbl))
>> -		return 0;
>> +	int i, irq_count;
>> +	void *cb;
>> 
>>  	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++) {
>>  		spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> -		cb_count = 0;
>> -		irq_count = atomic_read(&dpu_kms->hw_intr->irq_counts[i]);
>> -		list_for_each_entry(cb, &dpu_kms->hw_intr->irq_cb_tbl[i], list)
>> -			cb_count++;
>> +		irq_count = atomic_read(&dpu_kms->hw_intr->irq_tbl[i].count);
>> +		cb = dpu_kms->hw_intr->irq_tbl[i].cb;
>>  		spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>> 
>> -		if (irq_count || cb_count)
>> -			seq_printf(s, "idx:%d irq:%d cb:%d\n",
>> -					i, irq_count, cb_count);
>> +		if (irq_count || cb)
>> +			seq_printf(s, "idx:%d irq:%d cb:%ps\n", i, irq_count, cb);
>>  	}
>> 
>>  	return 0;
>> @@ -560,15 +535,8 @@ void dpu_core_irq_preinstall(struct dpu_kms 
>> *dpu_kms)
>>  	dpu_disable_all_irqs(dpu_kms);
>>  	pm_runtime_put_sync(&dpu_kms->pdev->dev);
>> 
>> -	/* Create irq callbacks for all possible irq_idx */
>> -	dpu_kms->hw_intr->irq_cb_tbl = kcalloc(dpu_kms->hw_intr->total_irqs,
>> -			sizeof(struct list_head), GFP_KERNEL);
>> -	dpu_kms->hw_intr->irq_counts = kcalloc(dpu_kms->hw_intr->total_irqs,
>> -			sizeof(atomic_t), GFP_KERNEL);
>> -	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++) {
>> -		INIT_LIST_HEAD(&dpu_kms->hw_intr->irq_cb_tbl[i]);
>> -		atomic_set(&dpu_kms->hw_intr->irq_counts[i], 0);
>> -	}
>> +	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++)
>> +		atomic_set(&dpu_kms->hw_intr->irq_tbl[i].count, 0);
>>  }
>> 
>>  void dpu_core_irq_uninstall(struct dpu_kms *dpu_kms)
>> @@ -577,7 +545,7 @@ void dpu_core_irq_uninstall(struct dpu_kms 
>> *dpu_kms)
>> 
>>  	pm_runtime_get_sync(&dpu_kms->pdev->dev);
>>  	for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++)
>> -		if (!list_empty(&dpu_kms->hw_intr->irq_cb_tbl[i]))
>> +		if (dpu_kms->hw_intr->irq_tbl[i].cb)
>>  			DPU_ERROR("irq_idx=%d still enabled/registered\n", i);
>> 
>>  	dpu_clear_irqs(dpu_kms);
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>> index d50e78c9f148..9855e176b173 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>> @@ -40,19 +40,21 @@ enum dpu_hw_intr_reg {
>>   * @save_irq_status:  array of IRQ status reg storage created during 
>> init
>>   * @total_irqs: total number of irq_idx mapped in the hw_interrupts
>>   * @irq_lock:         spinlock for accessing IRQ resources
>> - * @irq_cb_tbl:       array of IRQ callbacks lists
>> - * @irq_counts:       array of IRQ counts
>> + * @irq_cb_tbl:       array of IRQ callbacks
>>   */
>>  struct dpu_hw_intr {
>>  	struct dpu_hw_blk_reg_map hw;
>> -	u32 *cache_irq_mask;
>> +	u32 cache_irq_mask[MDP_INTR_MAX];
>>  	u32 *save_irq_status;
>>  	u32 total_irqs;
>>  	spinlock_t irq_lock;
>>  	unsigned long irq_mask;
>> 
>> -	struct list_head *irq_cb_tbl;
>> -	atomic_t *irq_counts;
>> +	struct {
>> +		void (*cb)(void *arg, int irq_idx);
>> +		void *arg;
>> +		atomic_t count;
>> +	} irq_tbl[];
>>  };
>> 
>>  /**
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>> index 775bcbda860f..d24dcd852d2e 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>> @@ -66,18 +66,6 @@
>> 
>>  #define DPU_NAME_SIZE  12
>> 
>> -/*
>> - * struct dpu_irq_callback - IRQ callback handlers
>> - * @list: list to callback
>> - * @func: intr handler
>> - * @arg: argument for the handler
>> - */
>> -struct dpu_irq_callback {
>> -	struct list_head list;
>> -	void (*func)(void *arg, int irq_idx);
>> -	void *arg;
>> -};
>> -
>>  struct dpu_kms {
>>  	struct msm_kms base;
>>  	struct drm_device *dev;
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>> index 37bba57675a8..1e2619556f93 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>> @@ -876,25 +876,25 @@ TRACE_EVENT(dpu_pp_connect_ext_te,
>>  );
>> 
>>  DECLARE_EVENT_CLASS(dpu_core_irq_callback_template,
>> -	TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),
>> +	TP_PROTO(int irq_idx, void *callback),
>>  	TP_ARGS(irq_idx, callback),
>>  	TP_STRUCT__entry(
>>  		__field(	int,				irq_idx	)
>> -		__field(	struct dpu_irq_callback *,	callback)
>> +		__field(	void *,				callback)
>>  	),
>>  	TP_fast_assign(
>>  		__entry->irq_idx = irq_idx;
>>  		__entry->callback = callback;
>>  	),
>> -	TP_printk("irq_idx:%d callback:%pK", __entry->irq_idx,
>> +	TP_printk("irq_idx:%d callback:%ps", __entry->irq_idx,
>>  		  __entry->callback)
>>  );
>>  DEFINE_EVENT(dpu_core_irq_callback_template, 
>> dpu_core_irq_register_callback,
>> -	TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),
>> +	TP_PROTO(int irq_idx, void *callback),
>>  	TP_ARGS(irq_idx, callback)
>>  );
>>  DEFINE_EVENT(dpu_core_irq_callback_template, 
>> dpu_core_irq_unregister_callback,
>> -	TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),
>> +	TP_PROTO(int irq_idx, void *callback),
>>  	TP_ARGS(irq_idx, callback)
>>  );

On 19/01/2022 03:10, abhinavk@codeaurora.org wrote:
> <replying from my older email as i couldnt find this thread on my new one>
> 
> On 2021-08-17 20:30, abhinavk@codeaurora.org wrote:
>> On 2021-06-17 15:20, Dmitry Baryshkov wrote:
>>> DPU interrupts code allows multiple callbacks per interrut. In reality
>> /interrupt
>>> none of the interrupts is shared between blocks (and will probably never
>>> be). Drop support for registering multiple callbacks per interrupt to
>>> simplify interrupt handling code.
>>>
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>>
>> I need to check on why we had this design originally and we still do.
>> the idx with which we are registering today can generate only one hw 
>> interrupt.
>> But i am not sure if something for planned for future use. Will update
>> in a day or two.
>>
>> meanwhile some comments and questions below.
> 
> I did check internally on the original design of this and yes the plan 
> was for other
> sub-modules to register for callbacks and that callback goes into the 
> callback list.
> 
> For example, lets say for some reason some other modules like the DSI 
> want to register
> for the VSYNC interrupt, it can register for a callback and that will 
> get added to the
> callback list.
> 
> But, this never got used that way and even now there is only one 
> callback per interrupt.
> We dont have a concrete use-case where we will need this in the future 
> but like many other things,
> we cannot tell for certain.
> 
> Since there is no concrete use-case where we might need this, if you 
> would like to go ahead
> with this, please do.
> 
> Once you address the other comments on this, I can ack this.

Thanks for the info. I'll respin this on top of current msm-next + 
https://patchwork.freedesktop.org/patch/464350/

> 
>>
>>> ---
>>>  drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h  |  18 +--
>>>  drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c   |   6 +-
>>>  .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h  |   2 +-
>>>  .../drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c  |  10 +-
>>>  .../drm/msm/disp/dpu1/dpu_encoder_phys_vid.c  |   6 +-
>>>  .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 144 +++++++-----------
>>>  .../gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h |  12 +-
>>>  drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h       |  12 --
>>>  drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h     |  10 +-
>>>  9 files changed, 86 insertions(+), 134 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>>> index 90ae6c9ccc95..44ab97fb2964 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_irq.h
>>> @@ -46,10 +46,8 @@ u32 dpu_core_irq_read(
>>>   *                             interrupt
>>>   * @dpu_kms:        DPU handle
>>>   * @irq_idx:        irq index
>>> - * @irq_cb:        IRQ callback structure, containing callback function
>>> - *            and argument. Passing NULL for irq_cb will unregister
>>> - *            the callback for the given irq_idx
>>> - *            This must exist until un-registration.
>>> + * @irq_cb:        IRQ callback funcion.
>>> + * @irq_arg:        IRQ callback argument.
>>>   * @return:        0 for success registering callback, otherwise 
>>> failure
>>>   *
>>>   * This function supports registration of multiple callbacks for each
>>> interrupt.
>>> @@ -57,17 +55,16 @@ u32 dpu_core_irq_read(
>>>  int dpu_core_irq_register_callback(
>>>          struct dpu_kms *dpu_kms,
>>>          int irq_idx,
>>> -        struct dpu_irq_callback *irq_cb);
>>> +        void (*irq_cb)(void *arg, int irq_idx),
>>> +        void *irq_arg);
>>>
>>>  /**
>>>   * dpu_core_irq_unregister_callback - For unregistering callback
>>> function on IRQ
>>>   *                             interrupt
>>>   * @dpu_kms:        DPU handle
>>>   * @irq_idx:        irq index
>>> - * @irq_cb:        IRQ callback structure, containing callback function
>>> - *            and argument. Passing NULL for irq_cb will unregister
>>> - *            the callback for the given irq_idx
>>> - *            This must match with registration.
>>> + * @irq_cb:        IRQ callback funcion.
>> /function
>> this typo is there in multiple places
>>> + * @irq_arg:        IRQ callback argument.
>>>   * @return:        0 for success registering callback, otherwise 
>>> failure
>>>   *
>>>   * This function supports registration of multiple callbacks for each
>>> interrupt.
>>> @@ -75,7 +72,8 @@ int dpu_core_irq_register_callback(
>>>  int dpu_core_irq_unregister_callback(
>>>          struct dpu_kms *dpu_kms,
>>>          int irq_idx,
>>> -        struct dpu_irq_callback *irq_cb);
>>> +        void (*irq_cb)(void *arg, int irq_idx),
>>> +        void *irq_arg);
>>>
>>>  /**
>>>   * dpu_debugfs_core_irq_init - register core irq debugfs
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> index 1c04b7cce43e..d3557b0f4db9 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>> @@ -310,7 +310,7 @@ int dpu_encoder_helper_wait_for_irq(struct
>>> dpu_encoder_phys *phys_enc,
>>>                        phys_enc->hw_pp->idx - PINGPONG_0,
>>>                        atomic_read(wait_info->atomic_cnt));
>>>              local_irq_save(flags);
>>> -            irq->cb.func(phys_enc, irq->irq_idx);
>>> +            irq->func(phys_enc, irq->irq_idx);
>>>              local_irq_restore(flags);
>>>              ret = 0;
>>>          } else {
>>> @@ -352,7 +352,7 @@ int dpu_encoder_helper_register_irq(struct
>>> dpu_encoder_phys *phys_enc,
>>>      }
>>>
>>>      ret = dpu_core_irq_register_callback(phys_enc->dpu_kms, 
>>> irq->irq_idx,
>>> -            &irq->cb);
>>> +            irq->func, phys_enc);
>>>      if (ret) {
>>>          DPU_ERROR_PHYS(phys_enc,
>>>              "failed to register IRQ callback for %s\n",
>>> @@ -384,7 +384,7 @@ int dpu_encoder_helper_unregister_irq(struct
>>> dpu_encoder_phys *phys_enc,
>>>      }
>>>
>>>      ret = dpu_core_irq_unregister_callback(phys_enc->dpu_kms, 
>>> irq->irq_idx,
>>> -            &irq->cb);
>>> +            irq->func, phys_enc);
>>>      if (ret) {
>>>          DRM_ERROR("unreg cb fail id=%u, intr=%d, irq=%d ret=%d",
>>>                DRMID(phys_enc->parent), intr_idx,
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>>> index e7270eb6b84b..80d87871fd94 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys.h
>>> @@ -174,7 +174,7 @@ struct dpu_encoder_irq {
>>>      const char *name;
>>>      enum dpu_intr_idx intr_idx;
>>>      int irq_idx;
>>> -    struct dpu_irq_callback cb;
>>> +    void (*func)(void *arg, int irq_idx);
>>>  };
>>>
>>>  /**
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>>> index aa01698d6b25..f921a5c99456 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>>> @@ -782,30 +782,28 @@ struct dpu_encoder_phys 
>>> *dpu_encoder_phys_cmd_init(
>>>      phys_enc->enable_state = DPU_ENC_DISABLED;
>>>      for (i = 0; i < INTR_IDX_MAX; i++) {
>>>          irq = &phys_enc->irq[i];
>>> -        INIT_LIST_HEAD(&irq->cb.list);
>>>          irq->irq_idx = -EINVAL;
>>> -        irq->cb.arg = phys_enc;
>>>      }
>>>
>>>      irq = &phys_enc->irq[INTR_IDX_CTL_START];
>>>      irq->name = "ctl_start";
>>>      irq->intr_idx = INTR_IDX_CTL_START;
>>> -    irq->cb.func = dpu_encoder_phys_cmd_ctl_start_irq;
>>> +    irq->func = dpu_encoder_phys_cmd_ctl_start_irq;
>>>
>>>      irq = &phys_enc->irq[INTR_IDX_PINGPONG];
>>>      irq->name = "pp_done";
>>>      irq->intr_idx = INTR_IDX_PINGPONG;
>>> -    irq->cb.func = dpu_encoder_phys_cmd_pp_tx_done_irq;
>>> +    irq->func = dpu_encoder_phys_cmd_pp_tx_done_irq;
>>>
>>>      irq = &phys_enc->irq[INTR_IDX_RDPTR];
>>>      irq->name = "pp_rd_ptr";
>>>      irq->intr_idx = INTR_IDX_RDPTR;
>>> -    irq->cb.func = dpu_encoder_phys_cmd_pp_rd_ptr_irq;
>>> +    irq->func = dpu_encoder_phys_cmd_pp_rd_ptr_irq;
>>>
>>>      irq = &phys_enc->irq[INTR_IDX_UNDERRUN];
>>>      irq->name = "underrun";
>>>      irq->intr_idx = INTR_IDX_UNDERRUN;
>>> -    irq->cb.func = dpu_encoder_phys_cmd_underrun_irq;
>>> +    irq->func = dpu_encoder_phys_cmd_underrun_irq;
>>>
>>>      atomic_set(&phys_enc->vblank_refcount, 0);
>>>      atomic_set(&phys_enc->pending_kickoff_cnt, 0);
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>>> index 185379b18572..437af231d6a4 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_vid.c
>>> @@ -725,20 +725,18 @@ struct dpu_encoder_phys 
>>> *dpu_encoder_phys_vid_init(
>>>      phys_enc->enc_spinlock = p->enc_spinlock;
>>>      for (i = 0; i < INTR_IDX_MAX; i++) {
>>>          irq = &phys_enc->irq[i];
>>> -        INIT_LIST_HEAD(&irq->cb.list);
>>>          irq->irq_idx = -EINVAL;
>>> -        irq->cb.arg = phys_enc;
>>>      }
>>>
>>>      irq = &phys_enc->irq[INTR_IDX_VSYNC];
>>>      irq->name = "vsync_irq";
>>>      irq->intr_idx = INTR_IDX_VSYNC;
>>> -    irq->cb.func = dpu_encoder_phys_vid_vblank_irq;
>>> +    irq->func = dpu_encoder_phys_vid_vblank_irq;
>>>
>>>      irq = &phys_enc->irq[INTR_IDX_UNDERRUN];
>>>      irq->name = "underrun";
>>>      irq->intr_idx = INTR_IDX_UNDERRUN;
>>> -    irq->cb.func = dpu_encoder_phys_vid_underrun_irq;
>>> +    irq->func = dpu_encoder_phys_vid_underrun_irq;
>>>
>>>      atomic_set(&phys_enc->vblank_refcount, 0);
>>>      atomic_set(&phys_enc->pending_kickoff_cnt, 0);
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>>> index d2b6dca487e3..7062e7f0e860 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>>> @@ -127,21 +127,17 @@ static const struct dpu_intr_reg dpu_intr_set[] 
>>> = {
>>>   */
>>>  static void dpu_core_irq_callback_handler(struct dpu_kms *dpu_kms, 
>>> int irq_idx)
>>>  {
>>> -    struct dpu_irq_callback *cb;
>>> -
>>>      VERB("irq_idx=%d\n", irq_idx);
>>>
>>> -    if (list_empty(&dpu_kms->hw_intr->irq_cb_tbl[irq_idx]))
>>> +    if (!dpu_kms->hw_intr->irq_tbl[irq_idx].cb)
>>>          DRM_ERROR("no registered cb, idx:%d\n", irq_idx);
>>>
>>> -    atomic_inc(&dpu_kms->hw_intr->irq_counts[irq_idx]);
>>> +    atomic_inc(&dpu_kms->hw_intr->irq_tbl[irq_idx].count);
>>>
>>>      /*
>>>       * Perform registered function callback
>>>       */
>>> -    list_for_each_entry(cb, &dpu_kms->hw_intr->irq_cb_tbl[irq_idx], 
>>> list)
>>> -        if (cb->func)
>>> -            cb->func(cb->arg, irq_idx);
>>> +    
>>> dpu_kms->hw_intr->irq_tbl[irq_idx].cb(dpu_kms->hw_intr->irq_tbl[irq_idx].arg, 
>>>
>>> irq_idx);
>>>  }
>>>
>>>  irqreturn_t dpu_core_irq(struct dpu_kms *dpu_kms)
>>> @@ -389,24 +385,18 @@ struct dpu_hw_intr *dpu_hw_intr_init(void 
>>> __iomem *addr,
>>>          struct dpu_mdss_cfg *m)
>>>  {
>>>      struct dpu_hw_intr *intr;
>>> +    int nirq = MDP_INTR_MAX * 32;
>>>
>>>      if (!addr || !m)
>>>          return ERR_PTR(-EINVAL);
>>>
>>> -    intr = kzalloc(sizeof(*intr), GFP_KERNEL);
>>> +    intr = kzalloc(struct_size(intr, irq_tbl, nirq), GFP_KERNEL);
>>>      if (!intr)
>>>          return ERR_PTR(-ENOMEM);
>>>
>>>      __intr_offset(m, addr, &intr->hw);
>>>
>>> -    intr->total_irqs = ARRAY_SIZE(dpu_intr_set) * 32;
>>> -
>>> -    intr->cache_irq_mask = kcalloc(ARRAY_SIZE(dpu_intr_set), 
>>> sizeof(u32),
>>> -            GFP_KERNEL);
>>> -    if (intr->cache_irq_mask == NULL) {
>>> -        kfree(intr);
>>> -        return ERR_PTR(-ENOMEM);
>>> -    }
>>> +    intr->total_irqs = nirq;
>>>
>>>      intr->irq_mask = m->mdss_irqs;
>>>
>>> @@ -417,31 +407,19 @@ struct dpu_hw_intr *dpu_hw_intr_init(void 
>>> __iomem *addr,
>>>
>>>  void dpu_hw_intr_destroy(struct dpu_hw_intr *intr)
>>>  {
>>> -    if (intr) {
>>> -        kfree(intr->cache_irq_mask);
>>> -
>>> -        kfree(intr->irq_cb_tbl);
>>> -        kfree(intr->irq_counts);
>>> -
>>> +    if (intr)
>>>          kfree(intr);
>>> -    }
>>>  }
>>>
>>>  int dpu_core_irq_register_callback(struct dpu_kms *dpu_kms, int 
>>> irq_idx,
>>> -        struct dpu_irq_callback *register_irq_cb)
>>> +        void (*irq_cb)(void *arg, int irq_idx),
>>> +        void *irq_arg)
>>>  {
>>>      unsigned long irq_flags;
>>> +    int ret;
>>>
>>> -    if (!dpu_kms->hw_intr->irq_cb_tbl) {
>>> -        DPU_ERROR("invalid params\n");
>>> -        return -EINVAL;
>>> -    }
>>> -
>>> -    if (!register_irq_cb || !register_irq_cb->func) {
>>> -        DPU_ERROR("invalid irq_cb:%d func:%d\n",
>>> -                register_irq_cb != NULL,
>>> -                register_irq_cb ?
>>> -                    register_irq_cb->func != NULL : -1);
>>> +    if (!irq_cb) {
>>> +        DPU_ERROR("invalid ird_idx:%d irq_cb:%ps\n", irq_idx, irq_cb);
>>>          return -EINVAL;
>>>      }
>>>
>>> @@ -453,39 +431,37 @@ int dpu_core_irq_register_callback(struct
>>> dpu_kms *dpu_kms, int irq_idx,
>>>      VERB("[%pS] irq_idx=%d\n", __builtin_return_address(0), irq_idx);
>>>
>>>      spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>> -    trace_dpu_core_irq_register_callback(irq_idx, register_irq_cb);
>>> -    list_del_init(&register_irq_cb->list);
>>> -    list_add_tail(&register_irq_cb->list,
>>> -            &dpu_kms->hw_intr->irq_cb_tbl[irq_idx]);
>>> -    if (list_is_first(&register_irq_cb->list,
>>> -            &dpu_kms->hw_intr->irq_cb_tbl[irq_idx])) {
>>> -        int ret = dpu_hw_intr_enable_irq_locked(
>>> +
>>> +    if (dpu_kms->hw_intr->irq_tbl[irq_idx].cb) {
>>> +        spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>> +
>>> +        return -EBUSY;
>>> +    }
>> Why is this check present? Ideally there should be only one callback 
>> registered.

There should be one callback registered. However I'd prefer to be safe 
than sorry and to warn if somebody attempts to register a second 
callback here.

>>> +
>>> +    trace_dpu_core_irq_register_callback(irq_idx, irq_cb);
>>> +    dpu_kms->hw_intr->irq_tbl[irq_idx].arg = irq_arg;
>>> +    dpu_kms->hw_intr->irq_tbl[irq_idx].cb = irq_cb;
>>> +
>>> +    ret = dpu_hw_intr_enable_irq_locked(
>>>                  dpu_kms->hw_intr,
>>>                  irq_idx);
>>> -        if (ret)
>>> -            DPU_ERROR("Fail to enable IRQ for irq_idx:%d\n",
>>> +    if (ret)
>>> +        DPU_ERROR("Fail to enable IRQ for irq_idx:%d\n",
>>>                      irq_idx);
>>> -    }
>>>      spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>>
>>>      return 0;
>>>  }
>>>
>>>  int dpu_core_irq_unregister_callback(struct dpu_kms *dpu_kms, int 
>>> irq_idx,
>>> -        struct dpu_irq_callback *register_irq_cb)
>>> +        void (*irq_cb)(void *arg, int irq_idx),
>>> +        void *irq_arg)
>>>  {
>>>      unsigned long irq_flags;
>>> +    int ret;
>>>
>>> -    if (!dpu_kms->hw_intr->irq_cb_tbl) {
>>> -        DPU_ERROR("invalid params\n");
>>> -        return -EINVAL;
>>> -    }
>>> -
>>> -    if (!register_irq_cb || !register_irq_cb->func) {
>>> -        DPU_ERROR("invalid irq_cb:%d func:%d\n",
>>> -                register_irq_cb != NULL,
>>> -                register_irq_cb ?
>>> -                    register_irq_cb->func != NULL : -1);
>>> +    if (!irq_cb) {
>>> +        DPU_ERROR("invalid ird_idx:%d irq_cb:%ps\n", irq_idx, irq_cb);
>>>          return -EINVAL;
>>>      }
>>>
>>> @@ -497,18 +473,23 @@ int dpu_core_irq_unregister_callback(struct
>>> dpu_kms *dpu_kms, int irq_idx,
>>>      VERB("[%pS] irq_idx=%d\n", __builtin_return_address(0), irq_idx);
>>>
>>>      spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>> -    trace_dpu_core_irq_unregister_callback(irq_idx, register_irq_cb);
>>> -    list_del_init(&register_irq_cb->list);
>>> -    /* empty callback list but interrupt is still enabled */
>>> -    if (list_empty(&dpu_kms->hw_intr->irq_cb_tbl[irq_idx])) {
>>> -        int ret = dpu_hw_intr_disable_irq_locked(
>>> -                dpu_kms->hw_intr,
>>> -                irq_idx);
>>> -        if (ret)
>>> -            DPU_ERROR("Fail to disable IRQ for irq_idx:%d\n",
>>> -                    irq_idx);
>>> -        VERB("irq_idx=%d ret=%d\n", irq_idx, ret);
>>> +    trace_dpu_core_irq_unregister_callback(irq_idx, irq_cb);
>>> +
>>> +    if (WARN_ON(dpu_kms->hw_intr->irq_tbl[irq_idx].cb != irq_cb ||
>>> +            dpu_kms->hw_intr->irq_tbl[irq_idx].arg != irq_arg)) {
>>> +        spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>> +
>>> +        return -EINVAL;
>>>      }
>>
>> Why do we need this check too? Any condition where this wont match?

No, we can drop this.

>>
>>> +
>>> +    ret = dpu_hw_intr_disable_irq_locked(dpu_kms->hw_intr, irq_idx);
>>> +    if (ret)
>>> +        DPU_ERROR("Fail to disable IRQ for irq_idx:%d: %d\n",
>>> +                    irq_idx, ret);
>>> +
>>> +    dpu_kms->hw_intr->irq_tbl[irq_idx].cb = NULL;
>>> +    dpu_kms->hw_intr->irq_tbl[irq_idx].arg = NULL;
>>> +
>>>      spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>>
>>>      return 0;
>>> @@ -518,24 +499,18 @@ int dpu_core_irq_unregister_callback(struct
>>> dpu_kms *dpu_kms, int irq_idx,
>>>  static int dpu_debugfs_core_irq_show(struct seq_file *s, void *v)
>>>  {
>>>      struct dpu_kms *dpu_kms = s->private;
>>> -    struct dpu_irq_callback *cb;
>>>      unsigned long irq_flags;
>>> -    int i, irq_count, cb_count;
>>> -
>>> -    if (WARN_ON(!dpu_kms->hw_intr->irq_cb_tbl))
>>> -        return 0;
>>> +    int i, irq_count;
>>> +    void *cb;
>>>
>>>      for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++) {
>>>          spin_lock_irqsave(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>> -        cb_count = 0;
>>> -        irq_count = atomic_read(&dpu_kms->hw_intr->irq_counts[i]);
>>> -        list_for_each_entry(cb, &dpu_kms->hw_intr->irq_cb_tbl[i], list)
>>> -            cb_count++;
>>> +        irq_count = atomic_read(&dpu_kms->hw_intr->irq_tbl[i].count);
>>> +        cb = dpu_kms->hw_intr->irq_tbl[i].cb;
>>>          spin_unlock_irqrestore(&dpu_kms->hw_intr->irq_lock, irq_flags);
>>>
>>> -        if (irq_count || cb_count)
>>> -            seq_printf(s, "idx:%d irq:%d cb:%d\n",
>>> -                    i, irq_count, cb_count);
>>> +        if (irq_count || cb)
>>> +            seq_printf(s, "idx:%d irq:%d cb:%ps\n", i, irq_count, cb);
>>>      }
>>>
>>>      return 0;
>>> @@ -560,15 +535,8 @@ void dpu_core_irq_preinstall(struct dpu_kms 
>>> *dpu_kms)
>>>      dpu_disable_all_irqs(dpu_kms);
>>>      pm_runtime_put_sync(&dpu_kms->pdev->dev);
>>>
>>> -    /* Create irq callbacks for all possible irq_idx */
>>> -    dpu_kms->hw_intr->irq_cb_tbl = 
>>> kcalloc(dpu_kms->hw_intr->total_irqs,
>>> -            sizeof(struct list_head), GFP_KERNEL);
>>> -    dpu_kms->hw_intr->irq_counts = 
>>> kcalloc(dpu_kms->hw_intr->total_irqs,
>>> -            sizeof(atomic_t), GFP_KERNEL);
>>> -    for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++) {
>>> -        INIT_LIST_HEAD(&dpu_kms->hw_intr->irq_cb_tbl[i]);
>>> -        atomic_set(&dpu_kms->hw_intr->irq_counts[i], 0);
>>> -    }
>>> +    for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++)
>>> +        atomic_set(&dpu_kms->hw_intr->irq_tbl[i].count, 0);
>>>  }
>>>
>>>  void dpu_core_irq_uninstall(struct dpu_kms *dpu_kms)
>>> @@ -577,7 +545,7 @@ void dpu_core_irq_uninstall(struct dpu_kms *dpu_kms)
>>>
>>>      pm_runtime_get_sync(&dpu_kms->pdev->dev);
>>>      for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++)
>>> -        if (!list_empty(&dpu_kms->hw_intr->irq_cb_tbl[i]))
>>> +        if (dpu_kms->hw_intr->irq_tbl[i].cb)
>>>              DPU_ERROR("irq_idx=%d still enabled/registered\n", i);
>>>
>>>      dpu_clear_irqs(dpu_kms);
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>>> index d50e78c9f148..9855e176b173 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h
>>> @@ -40,19 +40,21 @@ enum dpu_hw_intr_reg {
>>>   * @save_irq_status:  array of IRQ status reg storage created during 
>>> init
>>>   * @total_irqs: total number of irq_idx mapped in the hw_interrupts
>>>   * @irq_lock:         spinlock for accessing IRQ resources
>>> - * @irq_cb_tbl:       array of IRQ callbacks lists
>>> - * @irq_counts:       array of IRQ counts
>>> + * @irq_cb_tbl:       array of IRQ callbacks
>>>   */
>>>  struct dpu_hw_intr {
>>>      struct dpu_hw_blk_reg_map hw;
>>> -    u32 *cache_irq_mask;
>>> +    u32 cache_irq_mask[MDP_INTR_MAX];
>>>      u32 *save_irq_status;
>>>      u32 total_irqs;
>>>      spinlock_t irq_lock;
>>>      unsigned long irq_mask;
>>>
>>> -    struct list_head *irq_cb_tbl;
>>> -    atomic_t *irq_counts;
>>> +    struct {
>>> +        void (*cb)(void *arg, int irq_idx);
>>> +        void *arg;
>>> +        atomic_t count;
>>> +    } irq_tbl[];
>>>  };
>>>
>>>  /**
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>>> index 775bcbda860f..d24dcd852d2e 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>>> @@ -66,18 +66,6 @@
>>>
>>>  #define DPU_NAME_SIZE  12
>>>
>>> -/*
>>> - * struct dpu_irq_callback - IRQ callback handlers
>>> - * @list: list to callback
>>> - * @func: intr handler
>>> - * @arg: argument for the handler
>>> - */
>>> -struct dpu_irq_callback {
>>> -    struct list_head list;
>>> -    void (*func)(void *arg, int irq_idx);
>>> -    void *arg;
>>> -};
>>> -
>>>  struct dpu_kms {
>>>      struct msm_kms base;
>>>      struct drm_device *dev;
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>>> index 37bba57675a8..1e2619556f93 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_trace.h
>>> @@ -876,25 +876,25 @@ TRACE_EVENT(dpu_pp_connect_ext_te,
>>>  );
>>>
>>>  DECLARE_EVENT_CLASS(dpu_core_irq_callback_template,
>>> -    TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),
>>> +    TP_PROTO(int irq_idx, void *callback),
>>>      TP_ARGS(irq_idx, callback),
>>>      TP_STRUCT__entry(
>>>          __field(    int,                irq_idx    )
>>> -        __field(    struct dpu_irq_callback *,    callback)
>>> +        __field(    void *,                callback)
>>>      ),
>>>      TP_fast_assign(
>>>          __entry->irq_idx = irq_idx;
>>>          __entry->callback = callback;
>>>      ),
>>> -    TP_printk("irq_idx:%d callback:%pK", __entry->irq_idx,
>>> +    TP_printk("irq_idx:%d callback:%ps", __entry->irq_idx,
>>>            __entry->callback)
>>>  );
>>>  DEFINE_EVENT(dpu_core_irq_callback_template, 
>>> dpu_core_irq_register_callback,
>>> -    TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),
>>> +    TP_PROTO(int irq_idx, void *callback),
>>>      TP_ARGS(irq_idx, callback)
>>>  );
>>>  DEFINE_EVENT(dpu_core_irq_callback_template, 
>>> dpu_core_irq_unregister_callback,
>>> -    TP_PROTO(int irq_idx, struct dpu_irq_callback *callback),
>>> +    TP_PROTO(int irq_idx, void *callback),
>>>      TP_ARGS(irq_idx, callback)
>>>  );