ath10k: Don't always treat modem stop events as crashes

When rebooting on sc7180 Trogdor devices I see the following crash from
the wifi driver.

 ath10k_snoc 18800000.wifi: firmware crashed! (guid 83493570-29a2-4e98-a83e-70048c47669c)

This is because a modem stop event looks just like a firmware crash to
the driver, the qmi connection is closed in both cases. Use the qcom ssr
notifier block to stop treating the qmi connection close event as a
firmware crash signal when the modem hasn't actually crashed. See
ath10k_qmi_event_server_exit() for more details.

This silences the crash message seen during every reboot.

Fixes: 3f14b73c3843 ("ath10k: Enable MSA region dump support for WCN3990")
Cc: Govind Singh <govinds@codeaurora.org>
Cc: Youghandhar Chintala <youghand@codeaurora.org>
Cc: Abhishek Kumar <kuabhs@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
 drivers/net/wireless/ath/ath10k/snoc.c | 75 ++++++++++++++++++++++++++
 drivers/net/wireless/ath/ath10k/snoc.h |  4 ++
 2 files changed, 79 insertions(+)


base-commit: 7d2a07b769330c34b4deabeed939325c77a7ec2f

On 9/5/21 4:04 PM, Stephen Boyd wrote:
> When rebooting on sc7180 Trogdor devices I see the following crash from
> the wifi driver.
>
>  ath10k_snoc 18800000.wifi: firmware crashed! (guid 83493570-29a2-4e98-a83e-70048c47669c)
>
> This is because a modem stop event looks just like a firmware crash to
> the driver, the qmi connection is closed in both cases. Use the qcom ssr
> notifier block to stop treating the qmi connection close event as a
> firmware crash signal when the modem hasn't actually crashed. See
> ath10k_qmi_event_server_exit() for more details.
>
> This silences the crash message seen during every reboot.
>
> Fixes: 3f14b73c3843 ("ath10k: Enable MSA region dump support for WCN3990")
> Cc: Govind Singh <govinds@codeaurora.org>
> Cc: Youghandhar Chintala <youghand@codeaurora.org>
> Cc: Abhishek Kumar <kuabhs@chromium.org>
> Signed-off-by: Stephen Boyd <swboyd@chromium.org>
> ---
>  drivers/net/wireless/ath/ath10k/snoc.c | 75 ++++++++++++++++++++++++++
>  drivers/net/wireless/ath/ath10k/snoc.h |  4 ++
>  2 files changed, 79 insertions(+)
>
> diff --git a/drivers/net/wireless/ath/ath10k/snoc.c b/drivers/net/wireless/ath/ath10k/snoc.c
> index ea00fbb15601..fc4970e063f8 100644
> --- a/drivers/net/wireless/ath/ath10k/snoc.c
> +++ b/drivers/net/wireless/ath/ath10k/snoc.c
> @@ -12,6 +12,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/property.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/remoteproc/qcom_rproc.h>
>  #include <linux/of_address.h>
>  #include <linux/iommu.h>
>  
> @@ -1477,6 +1478,70 @@ void ath10k_snoc_fw_crashed_dump(struct ath10k *ar)
>  	mutex_unlock(&ar->dump_mutex);
>  }
>  
> +static int ath10k_snoc_modem_notify(struct notifier_block *nb, unsigned long action,
> +				    void *data)
> +{
> +	struct ath10k_snoc *ar_snoc = container_of(nb, struct ath10k_snoc, nb);
> +	struct ath10k *ar = ar_snoc->ar;
> +	struct qcom_ssr_notify_data *notify_data = data;
> +
> +	switch (action) {
> +	case QCOM_SSR_BEFORE_POWERUP:
> +		ath10k_dbg(ar, ATH10K_DBG_SNOC, "received modem starting event\n");
> +		clear_bit(ATH10K_SNOC_FLAG_UNREGISTERING, &ar_snoc->flags);
> +		break;
> +
> +	case QCOM_SSR_AFTER_POWERUP:
> +		ath10k_dbg(ar, ATH10K_DBG_SNOC, "received modem running event\n");
> +		break;
> +
> +	case QCOM_SSR_BEFORE_SHUTDOWN:
> +		ath10k_dbg(ar, ATH10K_DBG_SNOC, "received modem %s event\n",
> +			   notify_data->crashed ? "crashed" : "stopping");
> +		if (!notify_data->crashed)
> +			set_bit(ATH10K_SNOC_FLAG_UNREGISTERING, &ar_snoc->flags);
> +		else
> +			clear_bit(ATH10K_SNOC_FLAG_UNREGISTERING, &ar_snoc->flags);
> +		break;
> +
> +	case QCOM_SSR_AFTER_SHUTDOWN:
> +		ath10k_dbg(ar, ATH10K_DBG_SNOC, "received modem offline event\n");
> +		break;
> +
> +	default:
> +		ath10k_err(ar, "received unrecognized event %lu\n", action);
> +		break;
> +	}
> +
> +	return NOTIFY_OK;
> +}
> +
> +static int ath10k_modem_init(struct ath10k *ar)
> +{
> +	struct ath10k_snoc *ar_snoc = ath10k_snoc_priv(ar);
> +	void *notifier;
> +
> +	ar_snoc->nb.notifier_call = ath10k_snoc_modem_notify;
> +
> +	notifier = qcom_register_ssr_notifier("mpss", &ar_snoc->nb);
> +	if (IS_ERR(notifier))
> +		return PTR_ERR(notifier);
> +
> +	ar_snoc->notifier = notifier;
> +
> +	return 0;
> +}
> +
> +static void ath10k_modem_deinit(struct ath10k *ar)
> +{
> +	int ret;
> +	struct ath10k_snoc *ar_snoc = ath10k_snoc_priv(ar);
> +
> +	ret = qcom_unregister_ssr_notifier(ar_snoc->notifier, &ar_snoc->nb);
> +	if (ret)
> +		ath10k_err(ar, "error %d unregistering notifier\n", ret);
> +}
> +
>  static int ath10k_setup_msa_resources(struct ath10k *ar, u32 msa_size)
>  {
>  	struct device *dev = ar->dev;
> @@ -1740,10 +1805,19 @@ static int ath10k_snoc_probe(struct platform_device *pdev)
>  		goto err_fw_deinit;
>  	}
>  
> +	ret = ath10k_modem_init(ar);
> +	if (ret) {
> +		ath10k_err(ar, "failed to initialize modem notifier: %d\n", ret);
> +		goto err_qmi_deinit;
> +	}
> +
>  	ath10k_dbg(ar, ATH10K_DBG_SNOC, "snoc probe\n");
>  
>  	return 0;
>  
> +err_qmi_deinit:
> +	ath10k_qmi_deinit(ar);
> +
>  err_fw_deinit:
>  	ath10k_fw_deinit(ar);
>  
> @@ -1771,6 +1845,7 @@ static int ath10k_snoc_free_resources(struct ath10k *ar)
>  	ath10k_fw_deinit(ar);
>  	ath10k_snoc_free_irq(ar);
>  	ath10k_snoc_release_resource(ar);
> +	ath10k_modem_deinit(ar);
>  	ath10k_qmi_deinit(ar);
>  	ath10k_core_destroy(ar);
>  
> diff --git a/drivers/net/wireless/ath/ath10k/snoc.h b/drivers/net/wireless/ath/ath10k/snoc.h
> index 5095d1893681..d986edc772f8 100644
> --- a/drivers/net/wireless/ath/ath10k/snoc.h
> +++ b/drivers/net/wireless/ath/ath10k/snoc.h
> @@ -6,6 +6,8 @@
>  #ifndef _SNOC_H_
>  #define _SNOC_H_
>  
> +#include <linux/notifier.h>
> +
>  #include "hw.h"
>  #include "ce.h"
>  #include "qmi.h"
> @@ -75,6 +77,8 @@ struct ath10k_snoc {
>  	struct clk_bulk_data *clks;
>  	size_t num_clks;
>  	struct ath10k_qmi *qmi;
> +	struct notifier_block nb;
> +	void *notifier;
>  	unsigned long flags;
>  	bool xo_cal_supported;
>  	u32 xo_cal_data;
>
> base-commit: 7d2a07b769330c34b4deabeed939325c77a7ec2f


I was also seeing this on the Lenovo Yoga C630, so I pulled the patch in
to test here and after testing 20 reboots, I have not seen the message once.

Tested-By: Steev Klimaszewski <steev@kali.org>

Quoting Matthias Kaehlcke (2021-09-07 12:32:59)
> On Sun, Sep 05, 2021 at 02:04:00PM -0700, Stephen Boyd wrote:
> > @@ -1740,10 +1805,19 @@ static int ath10k_snoc_probe(struct platform_device *pdev)
> >               goto err_fw_deinit;
> >       }
> >
> > +     ret = ath10k_modem_init(ar);
> > +     if (ret) {
> > +             ath10k_err(ar, "failed to initialize modem notifier: %d\n", ret);
>
> nit: ath10k_modem_init() encapsulates/hides the setup of the notifier,
> the error message should be inside the function, as for _deinit()

Sure. I can fix it. I was also wondering if I should drop the debug
prints for the cases that don't matter in the switch statement but I'll
just leave that alone unless someone complains about it.

The way I see this, this issue is happening because of a much bigger
design constraint. On integrated(modem+wifi) solutions, if remote proc
service is shutdown, it has a trickle down effect. It deinitializes
the modem processor (which controls wifi as its subsystem) and the
wifi FW. As the fw de-initializes, we see the Delete server generated
by the wifi FW. The FW generates delete server qmi event and there is
no way on the host wifi driver to differentiate between delete event
generated from a FW crash and de-initialization due to remoteproc and
so we see the FW crash logs even during shutdown.

I would like to know what are Qualcomm's views on the design
constraint and any plans to reduce the rigidity. Also, will the FW
broadcast other qmi events(QRTR_TYPE_BYE for e.g.) during shutdown
(different from crash) ? If so then we can utilize that event and then
we don't even have to add dependency on remoteproc.

Overall this change should fix the issue, additionally I have one
comment below and would like other reviewers views.

>  #include <linux/regulator/consumer.h>
> +#include <linux/remoteproc/qcom_rproc.h>
>  #include <linux/of_address.h>
We are adding an external dependency here but since this is added in
snoc.c (which is for integrated solution only), I can expect if SNOC
is enabled, remote proc will be enabled as well, so it should be fine.

Reviewed-by: Abhishek Kumar <kuabhs@chromium.org>

On Tue, Sep 7, 2021 at 12:48 PM Stephen Boyd <swboyd@chromium.org> wrote:
>
> Quoting Matthias Kaehlcke (2021-09-07 12:32:59)
> > On Sun, Sep 05, 2021 at 02:04:00PM -0700, Stephen Boyd wrote:
> > > @@ -1740,10 +1805,19 @@ static int ath10k_snoc_probe(struct platform_device *pdev)
> > >               goto err_fw_deinit;
> > >       }
> > >
> > > +     ret = ath10k_modem_init(ar);
> > > +     if (ret) {
> > > +             ath10k_err(ar, "failed to initialize modem notifier: %d\n", ret);
> >
> > nit: ath10k_modem_init() encapsulates/hides the setup of the notifier,
> > the error message should be inside the function, as for _deinit()
>
> Sure. I can fix it. I was also wondering if I should drop the debug
> prints for the cases that don't matter in the switch statement but I'll
> just leave that alone unless someone complains about it.

Quoting Abhishek Kumar (2021-09-08 15:37:07)
>
> Overall this change should fix the issue, additionally I have one
> comment below and would like other reviewers views.
>
> >  #include <linux/regulator/consumer.h>
> > +#include <linux/remoteproc/qcom_rproc.h>
> >  #include <linux/of_address.h>
> We are adding an external dependency here but since this is added in
> snoc.c (which is for integrated solution only), I can expect if SNOC
> is enabled, remote proc will be enabled as well, so it should be fine.

There are stubs so that if it isn't enabled it won't do anything. But as
you say SNOC relies on the modem to boot, so maybe CONFIG_ATH10K_SNOC
should depend on some remoteproc config anyway? I'm not clear how probe
ordering works but I think we'll want to make sure that we only register
the notifier once the remoteproc driver for the modem adds itself to the
list of available strings to look for.