Re: [PATCH v3 5/5] drm/amdgpu: do not resume device in thaw for normal hibernation

["Lazar, Lijo" <lijo.lazar@amd.com>]

On 7/8/2025 1:12 PM, 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>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 4f8632737574..10827becf855 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
> @@ -2654,8 +2658,17 @@ static int amdgpu_pmops_freeze(struct device *dev)
>  static int amdgpu_pmops_thaw(struct device *dev)
>  {
>  	struct drm_device *drm_dev = dev_get_drvdata(dev);
> +	int event = pm_transition_event();
>  
> -	return amdgpu_device_resume(drm_dev, true);
> +	switch (event) {
> +	case PM_EVENT_THAW: /* normal case */
> +		return 0;
> +	case PM_EVENT_RECOVER: /* error case */
> +		return amdgpu_device_resume(drm_dev, true);
> +	default:
> +		pr_err("unknown pm_transition_event %d\n", event);

If it ever happens, keeping a bit more context with 'dev_err' helps -
"unknown pm transition event during thaw %d"

With that -

	Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>

Thanks,
Lijo

> +		return -EOPNOTSUPP;
> +	}
>  }
>  
>  static int amdgpu_pmops_poweroff(struct device *dev)