Re: [PATCH 1/2] drm/msm/gpu: Wait for idle before suspending

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Thu 06 Jan 10:14 PST 2022, Rob Clark wrote:

> From: Rob Clark <robdclark@chromium.org>
> 
> System suspend uses pm_runtime_force_suspend(), which cheekily bypasses
> the runpm reference counts.  This doesn't actually work so well when the
> GPU is active.  So add a reasonable delay waiting for the GPU to become
> idle.
> 
> Alternatively we could just return -EBUSY in this case, but that has the
> disadvantage of causing system suspend to fail.
> 

Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> Signed-off-by: Rob Clark <robdclark@chromium.org>
> ---
>  drivers/gpu/drm/msm/adreno/adreno_device.c | 9 +++++++++
>  drivers/gpu/drm/msm/msm_gpu.c              | 3 +++
>  drivers/gpu/drm/msm/msm_gpu.h              | 3 +++
>  3 files changed, 15 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c
> index 93005839b5da..b677ca3fd75e 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_device.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
> @@ -611,6 +611,15 @@ static int adreno_resume(struct device *dev)
>  static int adreno_suspend(struct device *dev)
>  {
>  	struct msm_gpu *gpu = dev_to_gpu(dev);
> +	int ret = 0;
> +
> +	ret = wait_event_timeout(gpu->retire_event,
> +				 !msm_gpu_active(gpu),
> +				 msecs_to_jiffies(1000));
> +	if (ret == 0) {
> +		dev_err(dev, "Timeout waiting for GPU to suspend\n");
> +		return -EBUSY;
> +	}
>  
>  	return gpu->funcs->pm_suspend(gpu);
>  }
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index 0f78c2615272..2c1049c0ea14 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -703,6 +703,8 @@ static void retire_submits(struct msm_gpu *gpu)
>  			}
>  		}
>  	}
> +
> +	wake_up_all(&gpu->retire_event);
>  }
>  
>  static void retire_worker(struct kthread_work *work)
> @@ -848,6 +850,7 @@ int msm_gpu_init(struct drm_device *drm, struct platform_device *pdev,
>  	INIT_LIST_HEAD(&gpu->active_list);
>  	mutex_init(&gpu->active_lock);
>  	mutex_init(&gpu->lock);
> +	init_waitqueue_head(&gpu->retire_event);
>  	kthread_init_work(&gpu->retire_work, retire_worker);
>  	kthread_init_work(&gpu->recover_work, recover_worker);
>  	kthread_init_work(&gpu->fault_work, fault_worker);
> diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> index 445c6bfd4b6b..92aa1e9196c6 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.h
> +++ b/drivers/gpu/drm/msm/msm_gpu.h
> @@ -230,6 +230,9 @@ struct msm_gpu {
>  	/* work for handling GPU recovery: */
>  	struct kthread_work recover_work;
>  
> +	/** retire_event: notified when submits are retired: */
> +	wait_queue_head_t retire_event;
> +
>  	/* work for handling active-list retiring: */
>  	struct kthread_work retire_work;
>  
> -- 
> 2.33.1
>