[v7,4/6] clk: qcom: gpucc-sc7280: Add cx collapse reset support

Allow a consumer driver to poll for cx gdsc collapse through Reset
framework.

Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
---

(no changes since v3)

Changes in v3:
- Convert 'struct qcom_reset_ops cx_gdsc_reset' to 'static const' (Krzysztof)

Changes in v2:
- Minor update to use the updated custom reset ops implementation

 drivers/clk/qcom/gpucc-sc7280.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

On Wed, 5 Oct 2022 at 11:08, Akhil P Oommen <quic_akhilpo@quicinc.com> wrote:
>
> Allow a consumer driver to poll for cx gdsc collapse through Reset
> framework.

Would you mind extending this commit message, to allow us to better
understand what part is really the consumer part.

I was expecting the consumer part to be the GPU (adreno) driver, but I
may have failed to understand correctly. It would be nice to see an
example of a typical sequence, where the reset is being
asserted/deasserted, from the consumer point of view. Would you mind
explaining this a bit more?

>
> Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Kind regards
Uffe

> ---
>
> (no changes since v3)
>
> Changes in v3:
> - Convert 'struct qcom_reset_ops cx_gdsc_reset' to 'static const' (Krzysztof)
>
> Changes in v2:
> - Minor update to use the updated custom reset ops implementation
>
>  drivers/clk/qcom/gpucc-sc7280.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/drivers/clk/qcom/gpucc-sc7280.c b/drivers/clk/qcom/gpucc-sc7280.c
> index 9a832f2..fece3f4 100644
> --- a/drivers/clk/qcom/gpucc-sc7280.c
> +++ b/drivers/clk/qcom/gpucc-sc7280.c
> @@ -433,12 +433,22 @@ static const struct regmap_config gpu_cc_sc7280_regmap_config = {
>         .fast_io = true,
>  };
>
> +static const struct qcom_reset_ops cx_gdsc_reset = {
> +       .reset = gdsc_wait_for_collapse,
> +};
> +
> +static const struct qcom_reset_map gpucc_sc7280_resets[] = {
> +       [GPU_CX_COLLAPSE] = { .ops = &cx_gdsc_reset, .priv = &cx_gdsc },
> +};
> +
>  static const struct qcom_cc_desc gpu_cc_sc7280_desc = {
>         .config = &gpu_cc_sc7280_regmap_config,
>         .clks = gpu_cc_sc7280_clocks,
>         .num_clks = ARRAY_SIZE(gpu_cc_sc7280_clocks),
>         .gdscs = gpu_cc_sc7180_gdscs,
>         .num_gdscs = ARRAY_SIZE(gpu_cc_sc7180_gdscs),
> +       .resets = gpucc_sc7280_resets,
> +       .num_resets = ARRAY_SIZE(gpucc_sc7280_resets),
>  };
>
>  static const struct of_device_id gpu_cc_sc7280_match_table[] = {
> --
> 2.7.4
>

On 12/7/2022 9:16 PM, Ulf Hansson wrote:
> On Wed, 5 Oct 2022 at 11:08, Akhil P Oommen <quic_akhilpo@quicinc.com> wrote:
>> Allow a consumer driver to poll for cx gdsc collapse through Reset
>> framework.
> Would you mind extending this commit message, to allow us to better
> understand what part is really the consumer part.
Sure. I can do that.
>
> I was expecting the consumer part to be the GPU (adreno) driver, but I
> may have failed to understand correctly. It would be nice to see an
> example of a typical sequence, where the reset is being
> asserted/deasserted, from the consumer point of view. Would you mind
> explaining this a bit more?
https://elixir.bootlin.com/linux/v6.1-rc8/source/drivers/gpu/drm/msm/adreno/a6xx_gpu.c#L1309
You are correct. The consumer is adreno gpu driver. When there is a gpu fault, these sequences are followed:
1. drop pm_runtime_put() for gpu device which will drops its vote on 'cx' genpd. line: 1306
2. At this point, there could be vote from either smmu driver (smmu is under same power domain too) or from other subsystems (tz/hyp).
3. So we call into gdsc driver through reset interface to poll the gdsc register to ensure it collapsed at least once. Line: 1309
4. Then we turn ON gpu. line:1314.

-Akhil.
>
>> Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Kind regards
> Uffe
>
>> ---
>>
>> (no changes since v3)
>>
>> Changes in v3:
>> - Convert 'struct qcom_reset_ops cx_gdsc_reset' to 'static const' (Krzysztof)
>>
>> Changes in v2:
>> - Minor update to use the updated custom reset ops implementation
>>
>>  drivers/clk/qcom/gpucc-sc7280.c | 10 ++++++++++
>>  1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/clk/qcom/gpucc-sc7280.c b/drivers/clk/qcom/gpucc-sc7280.c
>> index 9a832f2..fece3f4 100644
>> --- a/drivers/clk/qcom/gpucc-sc7280.c
>> +++ b/drivers/clk/qcom/gpucc-sc7280.c
>> @@ -433,12 +433,22 @@ static const struct regmap_config gpu_cc_sc7280_regmap_config = {
>>         .fast_io = true,
>>  };
>>
>> +static const struct qcom_reset_ops cx_gdsc_reset = {
>> +       .reset = gdsc_wait_for_collapse,
>> +};
>> +
>> +static const struct qcom_reset_map gpucc_sc7280_resets[] = {
>> +       [GPU_CX_COLLAPSE] = { .ops = &cx_gdsc_reset, .priv = &cx_gdsc },
>> +};
>> +
>>  static const struct qcom_cc_desc gpu_cc_sc7280_desc = {
>>         .config = &gpu_cc_sc7280_regmap_config,
>>         .clks = gpu_cc_sc7280_clocks,
>>         .num_clks = ARRAY_SIZE(gpu_cc_sc7280_clocks),
>>         .gdscs = gpu_cc_sc7180_gdscs,
>>         .num_gdscs = ARRAY_SIZE(gpu_cc_sc7180_gdscs),
>> +       .resets = gpucc_sc7280_resets,
>> +       .num_resets = ARRAY_SIZE(gpucc_sc7280_resets),
>>  };
>>
>>  static const struct of_device_id gpu_cc_sc7280_match_table[] = {
>> --
>> 2.7.4
>>

On Thu, Dec 08, 2022 at 08:54:39PM +0530, Akhil P Oommen wrote:
> On 12/7/2022 9:16 PM, Ulf Hansson wrote:
> > On Wed, 5 Oct 2022 at 11:08, Akhil P Oommen <quic_akhilpo@quicinc.com> wrote:
> >> Allow a consumer driver to poll for cx gdsc collapse through Reset
> >> framework.
> > Would you mind extending this commit message, to allow us to better
> > understand what part is really the consumer part.
> Sure. I can do that.
> >
> > I was expecting the consumer part to be the GPU (adreno) driver, but I
> > may have failed to understand correctly. It would be nice to see an
> > example of a typical sequence, where the reset is being
> > asserted/deasserted, from the consumer point of view. Would you mind
> > explaining this a bit more?
> https://elixir.bootlin.com/linux/v6.1-rc8/source/drivers/gpu/drm/msm/adreno/a6xx_gpu.c#L1309
> You are correct. The consumer is adreno gpu driver. When there is a gpu fault, these sequences are followed:
> 1. drop pm_runtime_put() for gpu device which will drops its vote on 'cx' genpd. line: 1306
> 2. At this point, there could be vote from either smmu driver (smmu is under same power domain too) or from other subsystems (tz/hyp).

Can you confirm that this is happening completely independent of what
the kernel does?

> 3. So we call into gdsc driver through reset interface to poll the gdsc register to ensure it collapsed at least once. Line: 1309

I other words, if we engineered 1. such that it would wait in
gdsc_disable() until the condition for 3. is reached, that should work
for you? (Obviously depending on the ability for us to engineer this...)

Regards,
Bjorn

> 4. Then we turn ON gpu. line:1314.
> 
> -Akhil.
> >
> >> Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
> >> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > Kind regards
> > Uffe
> >
> >> ---
> >>
> >> (no changes since v3)
> >>
> >> Changes in v3:
> >> - Convert 'struct qcom_reset_ops cx_gdsc_reset' to 'static const' (Krzysztof)
> >>
> >> Changes in v2:
> >> - Minor update to use the updated custom reset ops implementation
> >>
> >>  drivers/clk/qcom/gpucc-sc7280.c | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> >>
> >> diff --git a/drivers/clk/qcom/gpucc-sc7280.c b/drivers/clk/qcom/gpucc-sc7280.c
> >> index 9a832f2..fece3f4 100644
> >> --- a/drivers/clk/qcom/gpucc-sc7280.c
> >> +++ b/drivers/clk/qcom/gpucc-sc7280.c
> >> @@ -433,12 +433,22 @@ static const struct regmap_config gpu_cc_sc7280_regmap_config = {
> >>         .fast_io = true,
> >>  };
> >>
> >> +static const struct qcom_reset_ops cx_gdsc_reset = {
> >> +       .reset = gdsc_wait_for_collapse,
> >> +};
> >> +
> >> +static const struct qcom_reset_map gpucc_sc7280_resets[] = {
> >> +       [GPU_CX_COLLAPSE] = { .ops = &cx_gdsc_reset, .priv = &cx_gdsc },
> >> +};
> >> +
> >>  static const struct qcom_cc_desc gpu_cc_sc7280_desc = {
> >>         .config = &gpu_cc_sc7280_regmap_config,
> >>         .clks = gpu_cc_sc7280_clocks,
> >>         .num_clks = ARRAY_SIZE(gpu_cc_sc7280_clocks),
> >>         .gdscs = gpu_cc_sc7180_gdscs,
> >>         .num_gdscs = ARRAY_SIZE(gpu_cc_sc7180_gdscs),
> >> +       .resets = gpucc_sc7280_resets,
> >> +       .num_resets = ARRAY_SIZE(gpucc_sc7280_resets),
> >>  };
> >>
> >>  static const struct of_device_id gpu_cc_sc7280_match_table[] = {
> >> --
> >> 2.7.4
> >>
>

On 12/9/2022 2:39 AM, Bjorn Andersson wrote:
> On Thu, Dec 08, 2022 at 08:54:39PM +0530, Akhil P Oommen wrote:
>> On 12/7/2022 9:16 PM, Ulf Hansson wrote:
>>> On Wed, 5 Oct 2022 at 11:08, Akhil P Oommen <quic_akhilpo@quicinc.com> wrote:
>>>> Allow a consumer driver to poll for cx gdsc collapse through Reset
>>>> framework.
>>> Would you mind extending this commit message, to allow us to better
>>> understand what part is really the consumer part.
>> Sure. I can do that.
>>> I was expecting the consumer part to be the GPU (adreno) driver, but I
>>> may have failed to understand correctly. It would be nice to see an
>>> example of a typical sequence, where the reset is being
>>> asserted/deasserted, from the consumer point of view. Would you mind
>>> explaining this a bit more?
>> https://elixir.bootlin.com/linux/v6.1-rc8/source/drivers/gpu/drm/msm/adreno/a6xx_gpu.c#L1309
>> You are correct. The consumer is adreno gpu driver. When there is a gpu fault, these sequences are followed:
>> 1. drop pm_runtime_put() for gpu device which will drops its vote on 'cx' genpd. line: 1306
>> 2. At this point, there could be vote from either smmu driver (smmu is under same power domain too) or from other subsystems (tz/hyp).
> Can you confirm that this is happening completely independent of what
> the kernel does?
Yes, it is independent.
>
>> 3. So we call into gdsc driver through reset interface to poll the gdsc register to ensure it collapsed at least once. Line: 1309
> I other words, if we engineered 1. such that it would wait in
> gdsc_disable() until the condition for 3. is reached, that should work
> for you? (Obviously depending on the ability for us to engineer this...)
Yes, it will work.

-Akhil.
>
> Regards,
> Bjorn
>
>> 4. Then we turn ON gpu. line:1314.
>>
>> -Akhil.
>>>> Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
>>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>>> Kind regards
>>> Uffe
>>>
>>>> ---
>>>>
>>>> (no changes since v3)
>>>>
>>>> Changes in v3:
>>>> - Convert 'struct qcom_reset_ops cx_gdsc_reset' to 'static const' (Krzysztof)
>>>>
>>>> Changes in v2:
>>>> - Minor update to use the updated custom reset ops implementation
>>>>
>>>>  drivers/clk/qcom/gpucc-sc7280.c | 10 ++++++++++
>>>>  1 file changed, 10 insertions(+)
>>>>
>>>> diff --git a/drivers/clk/qcom/gpucc-sc7280.c b/drivers/clk/qcom/gpucc-sc7280.c
>>>> index 9a832f2..fece3f4 100644
>>>> --- a/drivers/clk/qcom/gpucc-sc7280.c
>>>> +++ b/drivers/clk/qcom/gpucc-sc7280.c
>>>> @@ -433,12 +433,22 @@ static const struct regmap_config gpu_cc_sc7280_regmap_config = {
>>>>         .fast_io = true,
>>>>  };
>>>>
>>>> +static const struct qcom_reset_ops cx_gdsc_reset = {
>>>> +       .reset = gdsc_wait_for_collapse,
>>>> +};
>>>> +
>>>> +static const struct qcom_reset_map gpucc_sc7280_resets[] = {
>>>> +       [GPU_CX_COLLAPSE] = { .ops = &cx_gdsc_reset, .priv = &cx_gdsc },
>>>> +};
>>>> +
>>>>  static const struct qcom_cc_desc gpu_cc_sc7280_desc = {
>>>>         .config = &gpu_cc_sc7280_regmap_config,
>>>>         .clks = gpu_cc_sc7280_clocks,
>>>>         .num_clks = ARRAY_SIZE(gpu_cc_sc7280_clocks),
>>>>         .gdscs = gpu_cc_sc7180_gdscs,
>>>>         .num_gdscs = ARRAY_SIZE(gpu_cc_sc7180_gdscs),
>>>> +       .resets = gpucc_sc7280_resets,
>>>> +       .num_resets = ARRAY_SIZE(gpucc_sc7280_resets),
>>>>  };
>>>>
>>>>  static const struct of_device_id gpu_cc_sc7280_match_table[] = {
>>>> --
>>>> 2.7.4
>>>>