RE: [PATCH] drm/amdgpu: don't runtime suspend if there are displays attached (v2)

["Quan, Evan" <Evan.Quan@amd.com>]

[AMD Official Use Only]



> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of Alex
> Deucher
> Sent: Thursday, April 14, 2022 4:15 AM
> To: amd-gfx@lists.freedesktop.org
> Cc: Deucher, Alexander <Alexander.Deucher@amd.com>; Michele Ballabio
> <ballabio.m@gmail.com>
> Subject: [PATCH] drm/amdgpu: don't runtime suspend if there are displays
> attached (v2)
> 
> We normally runtime suspend when there are displays attached if they
> are in the DPMS off state, however, if something wakes the GPU
> we send a hotplug event on resume (in case any displays were connected
> while the GPU was in suspend) which can cause userspace to light
> up the displays again soon after they were turned off.
> 
> Prior to
> commit 087451f372bf76 ("drm/amdgpu: use generic fb helpers instead of
> setting up AMD own's."),
> the driver took a runtime pm reference when the fbdev emulation was
> enabled because we didn't implement proper shadowing support for
> vram access when the device was off so the device never runtime
> suspended when there was a console bound.  Once that commit landed,
> we now utilize the core fb helper implementation which properly
> handles the emulation, so runtime pm now suspends in cases where it did
> not before.  Ultimately, we need to sort out why runtime suspend in not
> working in this case for some users, but this should restore similar
> behavior to before.
> 
> v2: move check into runtime_suspend
> 
> Fixes: 087451f372bf76 ("drm/amdgpu: use generic fb helpers instead of
> setting up AMD own's.")
> Tested-by: Michele Ballabio <ballabio.m@gmail.com>
> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 107 ++++++++++++++++---
> -----
>  1 file changed, 72 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 4efaa183abcd..97a1aa02d76e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -2395,6 +2395,71 @@ static int amdgpu_pmops_restore(struct device
> *dev)
>  	return amdgpu_device_resume(drm_dev, true);
>  }
> 
> +static int amdgpu_runtime_idle_check_display(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_to_adev(drm_dev);
> +
> +	if (adev->mode_info.num_crtc) {
> +		struct drm_connector *list_connector;
> +		struct drm_connector_list_iter iter;
> +		int ret = 0;
> +
> +		/* XXX: Return busy if any displays are connected to avoid
> +		 * possible display wake ups after runtime resume due to
> +		 * hotplug events in case any displays were connected while
> +		 * the GPU was in suspend.  Remove this once that is fixed.
> +		 */
> +		mutex_lock(&drm_dev->mode_config.mutex);
> +		drm_connector_list_iter_begin(drm_dev, &iter);
> +		drm_for_each_connector_iter(list_connector, &iter) {
> +			if (list_connector->status ==
> connector_status_connected) {
> +				ret = -EBUSY;
> +				break;
> +			}
> +		}
> +		drm_connector_list_iter_end(&iter);
> +		mutex_unlock(&drm_dev->mode_config.mutex);
> +
> +		if (ret)
> +			return ret;
> +
> +		if (amdgpu_device_has_dc_support(adev)) {
> +			struct drm_crtc *crtc;
> +
> +			drm_for_each_crtc(crtc, drm_dev) {
> +				drm_modeset_lock(&crtc->mutex, NULL);
> +				if (crtc->state->active)
> +					ret = -EBUSY;
> +				drm_modeset_unlock(&crtc->mutex);
> +				if (ret < 0)
> +					break;
> +			}
> +		} else {
> +			mutex_lock(&drm_dev->mode_config.mutex);
> +			drm_modeset_lock(&drm_dev-
> >mode_config.connection_mutex, NULL);
> +
> +			drm_connector_list_iter_begin(drm_dev, &iter);
> +			drm_for_each_connector_iter(list_connector, &iter)
> {
> +				if (list_connector->dpms ==
> DRM_MODE_DPMS_ON) {
> +					ret = -EBUSY;
> +					break;
> +				}
> +			}
> +
> +			drm_connector_list_iter_end(&iter);
> +
> +			drm_modeset_unlock(&drm_dev-
> >mode_config.connection_mutex);
> +			mutex_unlock(&drm_dev->mode_config.mutex);
> +		}
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static int amdgpu_pmops_runtime_suspend(struct device *dev)
>  {
>  	struct pci_dev *pdev = to_pci_dev(dev);
> @@ -2407,6 +2472,10 @@ static int
> amdgpu_pmops_runtime_suspend(struct device *dev)
>  		return -EBUSY;
>  	}
> 
> +	ret = amdgpu_runtime_idle_check_display(dev);
> +	if (ret)
> +		return ret;
> +
>  	/* wait for all rings to drain before suspending */
>  	for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
>  		struct amdgpu_ring *ring = adev->rings[i];
> @@ -2516,41 +2585,9 @@ static int amdgpu_pmops_runtime_idle(struct
> device *dev)
>  		return -EBUSY;
>  	}
> 
> -	if (amdgpu_device_has_dc_support(adev)) {
> -		struct drm_crtc *crtc;
> -
> -		drm_for_each_crtc(crtc, drm_dev) {
> -			drm_modeset_lock(&crtc->mutex, NULL);
> -			if (crtc->state->active)
> -				ret = -EBUSY;
> -			drm_modeset_unlock(&crtc->mutex);
> -			if (ret < 0)
> -				break;
> -		}
> -
> -	} else {
> -		struct drm_connector *list_connector;
> -		struct drm_connector_list_iter iter;
> -
> -		mutex_lock(&drm_dev->mode_config.mutex);
> -		drm_modeset_lock(&drm_dev-
> >mode_config.connection_mutex, NULL);
> -
> -		drm_connector_list_iter_begin(drm_dev, &iter);
> -		drm_for_each_connector_iter(list_connector, &iter) {
> -			if (list_connector->dpms ==  DRM_MODE_DPMS_ON)
> {
> -				ret = -EBUSY;
> -				break;
> -			}
> -		}
> -
> -		drm_connector_list_iter_end(&iter);
> -
> -		drm_modeset_unlock(&drm_dev-
> >mode_config.connection_mutex);
> -		mutex_unlock(&drm_dev->mode_config.mutex);
> -	}
> -
> -	if (ret == -EBUSY)
> -		DRM_DEBUG_DRIVER("failing to power off - crtc active\n");
> +	ret = amdgpu_runtime_idle_check_display(dev);
> +	if (ret)
> +		return ret;
[Quan, Evan] Previously, the following actions(pm_runtime_mark_last_busy/pm_runtime_autosuspend) will be still performed even if ret is set as EBUSY.
But with the new changes, it will abort directly without the following actions performed.
Is that expected? Will that make any logical change?

BR
Evan
> 
>  	pm_runtime_mark_last_busy(dev);
>  	pm_runtime_autosuspend(dev);
> --
> 2.35.1