linux-kernel - Re: [PATCH v4 5/5] drm/amdgpu: do not resume device in thaw for normal hibernation

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Message-ID: <CAJZ5v0ibK49=fbXH2oy6jVSEo6iFD9EvYR8ivHCUpP3iaU=8=A@mail.gmail.com>
Date: Wed, 9 Jul 2025 09:13:48 +0200
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Samuel Zhang <guoqing.zhang@....com>
Cc: alexander.deucher@....com, christian.koenig@....com, rafael@...nel.org, 
	len.brown@...el.com, pavel@...nel.org, gregkh@...uxfoundation.org, 
	dakr@...nel.org, airlied@...il.com, simona@...ll.ch, ray.huang@....com, 
	matthew.auld@...el.com, matthew.brost@...el.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, 
	mario.limonciello@....com, lijo.lazar@....com, victor.zhao@....com, 
	haijun.chang@....com, Qing.Ma@....com, Owen.Zhang2@....com, 
	linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v4 5/5] drm/amdgpu: do not resume device in thaw for
 normal hibernation

On Wed, Jul 9, 2025 at 8:44 AM Samuel Zhang <guoqing.zhang@....com> 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@....com>
> Reviewed-by: Lijo Lazar <lijo.lazar@....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..c37285a8b2c5 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;
> +

You need to do analogous things in amdgpu_pmops_prepare() and
amdgpu_pmops_poweroff() AFAICS in case hibernation is carried out in
the "platform" mode.

>         /* 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:
> +               dev_err(dev, "unknown pm_transition_event %d\n", event);
> +               return -EOPNOTSUPP;
> +       }
>  }
>
>  static int amdgpu_pmops_poweroff(struct device *dev)
> --