Re: [PATCH v5 5/5] drm/amdgpu: do not resume device in thaw for normal hibernation

[Mario Limonciello <mario.limonciello@amd.com>]

On 7/9/2025 6:05 AM, Samuel Zhang wrote:
> For normal hibernation, GPU do not need to be resumed in thaw since it is
> not involved in writing the hibernation image. Skip resume in this case
> can reduce the hibernation time.
> 
> On VM with 8 * 192GB VRAM dGPUs, 98% VRAM usage and 1.7TB system memory,
> this can save 50 minutes.
> 
> Signed-off-by: Samuel Zhang <guoqing.zhang@amd.com>

I hand modified the patches for other changes missing from linux-next in 
your base.

I checked on an APU with an eDP display connected and from a VT 
hibernate does keep the display off now so this is definitely an 
improvement there too.

Tested-by: Mario Limonciello <mario.limonciello@amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 4f8632737574..b24c420983ef 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -2541,6 +2541,10 @@ amdgpu_pci_shutdown(struct pci_dev *pdev)
>   	if (amdgpu_ras_intr_triggered())
>   		return;
>   
> +	/* device maybe not resumed here, return immediately in this case */
> +	if (adev->in_s4 && adev->in_suspend)
> +		return;
> +
>   	/* if we are running in a VM, make sure the device
>   	 * torn down properly on reboot/shutdown.
>   	 * unfortunately we can't detect certain
> @@ -2557,6 +2561,10 @@ static int amdgpu_pmops_prepare(struct device *dev)
>   	struct drm_device *drm_dev = dev_get_drvdata(dev);
>   	struct amdgpu_device *adev = drm_to_adev(drm_dev);
>   
> +	/* device maybe not resumed here, return immediately in this case */
> +	if (adev->in_s4 && adev->in_suspend)
> +		return 0;
> +

Is this one right?  Don't we still want to call prepare() for all the HW 
IP blocks?  The eviction call that happens in prepare() is a no-op but 
there are other IP blocks with an prepare_suspend() callback like DCN.

That is I think you're destroying the optimization from commit 
50e0bae34fa6b ("drm/amd/display: Add and use new dm_prepare_suspend() 
callback") by adding this code here.


>   	/* Return a positive number here so
>   	 * DPM_FLAG_SMART_SUSPEND works properly
>   	 */
> @@ -2655,12 +2663,21 @@ static int amdgpu_pmops_thaw(struct device *dev)
>   {
>   	struct drm_device *drm_dev = dev_get_drvdata(dev);
>   
> +	/* do not resume device if it's normal hibernation */
> +	if (!pm_hibernate_is_recovering())
> +		return 0;
> +
>   	return amdgpu_device_resume(drm_dev, true);
>   }
>   
>   static int amdgpu_pmops_poweroff(struct device *dev)
>   {
>   	struct drm_device *drm_dev = dev_get_drvdata(dev);
> +	struct amdgpu_device *adev = drm_to_adev(drm_dev);
> +
> +	/* device maybe not resumed here, return immediately in this case */
> +	if (adev->in_s4 && adev->in_suspend)
> +		return 0;
>   
>   	return amdgpu_device_suspend(drm_dev, true);
>   }