[PATCH] drm/amdgpu: wait for all rings to drain before runtime suspending

[zhoucm1]

On 2019/12/11 上午6:08, Alex Deucher wrote:
> Add a safety check to runtime suspend to make sure all outstanding
> fences have signaled before we suspend.  Doesn't fix any known issue.
>
> We already do this via the fence driver suspend function, but we
> just force completion rather than bailing.  This bails on runtime
> suspend so we can try again later once the fences are signaled to
> avoid missing any outstanding work.

The idea sounds OK to me, but if you want to drain the rings, you should 
make sure no more submission, right?

So you should park all schedulers before waiting for all outstanding 
fences completed.

-David

>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 12 +++++++++++-
>   1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 2f367146c72c..81322b0a8acf 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -1214,13 +1214,23 @@ static int amdgpu_pmops_runtime_suspend(struct device *dev)
>   	struct pci_dev *pdev = to_pci_dev(dev);
>   	struct drm_device *drm_dev = pci_get_drvdata(pdev);
>   	struct amdgpu_device *adev = drm_dev->dev_private;
> -	int ret;
> +	int ret, i;
>   
>   	if (!adev->runpm) {
>   		pm_runtime_forbid(dev);
>   		return -EBUSY;
>   	}
>   
> +	/* wait for all rings to drain before suspending */
> +	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
> +		struct amdgpu_ring *ring = adev->rings[i];
> +		if (ring && ring->sched.ready) {
> +			ret = amdgpu_fence_wait_empty(ring);
> +			if (ret)
> +				return -EBUSY;
> +		}
> +	}
> +
>   	if (amdgpu_device_supports_boco(drm_dev))
>   		drm_dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
>   	drm_kms_helper_poll_disable(drm_dev);