On Sat, Jul 30, 2022 at 2:41 AM Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx> 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@xxxxxxxxxxx>
> ---
>
> Changes in v3:
> - Simplied the pm refcount drop since we have just a single refcount now
> for all active submits
>
> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 24 +++++++++++++++++++++---
> drivers/gpu/drm/msm/msm_gpu.c | 4 +---
> 2 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 42ed9a3..1b049c5 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -1193,7 +1193,7 @@ static void a6xx_recover(struct msm_gpu *gpu)
> {
> struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> - int i;
> + int i, active_submits;
>
> adreno_dump_info(gpu);
>
> @@ -1210,8 +1210,26 @@ 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);
> + pm_runtime_dont_use_autosuspend(&gpu->pdev->dev);
> +
> + /* active_submit won't change until we make a submission */
> + mutex_lock(&gpu->active_lock);
> + active_submits = gpu->active_submits;
> + mutex_unlock(&gpu->active_lock);
> +
> + /* Drop the rpm refcount from active submits */
> + if (active_submits)
> + pm_runtime_put(&gpu->pdev->dev);
Couldn't this race with an incoming submit triggering active_submits
to transition 0 -> 1? Moving the mutex_unlock() would solve this.
Actually, maybe just move the mutex_unlock() to the end of the entire
sequence. You could also clear gpu->active_submits and restore it
before unlocking, so you can drop the removal of the WARN_ON_ONCE
(patch 6/8) which should otherwise be squashed into this patch to keep
things bisectable
> +
> + /* And the final one from recover worker */
> + pm_runtime_put_sync(&gpu->pdev->dev);
> +
> + pm_runtime_use_autosuspend(&gpu->pdev->dev);
> +
> + if (active_submits)
> + 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 1945efb..07e55a6 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -426,9 +426,7 @@ 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);
Hmm, could this have some fallout on earlier gens?
I guess I should extend the igt msm_recovery test to run on things
prior to a6xx..
BR,
-R
>
> /*
> * Replay all remaining submits starting with highest priority
> @@ -445,7 +443,7 @@ static void recover_worker(struct kthread_work *work)
> }
> }
>
> - pm_runtime_put_sync(&gpu->pdev->dev);
> + pm_runtime_put(&gpu->pdev->dev);
>
> mutex_unlock(&gpu->lock);
>
> --
> 2.7.4
>
