[Freedreno] [PATCH 3/7] drm/msm: Fix cx collapse issue during recovery

[Akhil P Oommen]

On 7/7/2022 10:40 PM, Rob Clark wrote:
> On Thu, Jul 7, 2022 at 9:11 AM Akhil P Oommen <quic_akhilpo at quicinc.com> wrote:
>>
>> There are some hardware logic under CX domain. For a successful
>> recovery, we should ensure cx headswitch collapses to ensure all the
>> stale states are cleard out. This is especially true to for a6xx family
>> where we can GMU co-processor.
>>
>> Currently, cx doesn't collapse due to a devlink between gpu and its
>> smmu. So the *struct gpu device* needs to be runtime suspended to ensure
>> that the iommu driver removes its vote on cx gdsc.
>>
>> Signed-off-by: Akhil P Oommen <quic_akhilpo at quicinc.com>
>> ---
>>
>>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 16 ++++++++++++++--
>>   drivers/gpu/drm/msm/msm_gpu.c         |  2 --
>>   2 files changed, 14 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> index 42ed9a3..57a7ad5 100644
>> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
>> @@ -1210,8 +1210,20 @@ static void a6xx_recover(struct msm_gpu *gpu)
>>           */
>>          gmu_write(&a6xx_gpu->gmu, REG_A6XX_GMU_GMU_PWR_COL_KEEPALIVE, 0);
>>
>> -       gpu->funcs->pm_suspend(gpu);
>> -       gpu->funcs->pm_resume(gpu);
>> +       /*
>> +        * Now drop all the pm_runtime usage count to allow cx gdsc to collapse.
>> +        * First drop the usage count from all active submits
>> +        */
>> +       for (i = gpu->active_submits; i > 0; i--)
>> +               pm_runtime_put(&gpu->pdev->dev);
> 
> Would pm_runtime_force_suspend/resume() work instead?

I believe it is supposed to be used only during system sleep state 
transitions. Btw, we don't want pm_runtime_get() calls from elsewhere to 
fail by disabling RPM here.

-Akhil
> 
> BR,
> -R
> 
>> +
>> +       /* And the final one from recover worker */
>> +       pm_runtime_put_sync(&gpu->pdev->dev);
>> +
>> +       for (i = gpu->active_submits; i > 0; i--)
>> +               pm_runtime_get(&gpu->pdev->dev);
>> +
>> +       pm_runtime_get_sync(&gpu->pdev->dev);
>>
>>          msm_gpu_hw_init(gpu);
>>   }
>> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
>> index f75ff4b..48171b6 100644
>> --- a/drivers/gpu/drm/msm/msm_gpu.c
>> +++ b/drivers/gpu/drm/msm/msm_gpu.c
>> @@ -444,9 +444,7 @@ static void recover_worker(struct kthread_work *work)
>>                  /* retire completed submits, plus the one that hung: */
>>                  retire_submits(gpu);
>>
>> -               pm_runtime_get_sync(&gpu->pdev->dev);
>>                  gpu->funcs->recover(gpu);
>> -               pm_runtime_put_sync(&gpu->pdev->dev);
>>
>>                  /*
>>                   * Replay all remaining submits starting with highest priority
>> --
>> 2.7.4
>>