[PATCH 3/3] drm/amdgpu: skip kfd resume_process for dev_pm_ops.thaw()

[Alex Deucher]

On Tue, Jul 1, 2025 at 4:32 AM Christian König <christian.koenig at amd.com> wrote:
>
> On 01.07.25 10:03, Zhang, GuoQing (Sam) wrote:
> >
> > thaw() is called before writing the hiberation image to swap disk. See
> > the doc here.
> > https://github.com/torvalds/linux/blob/v6.14/Documentation/driver-api/pm/devices.rst?plain=1#L552 <https://github.com/torvalds/linux/blob/v6.14/Documentation/driver-api/pm/devices.rst?plain=1#L552>
> >
> > And amdgpu implemented thaw() callback by calling amdgpu_device_resume().
> > https://github.com/torvalds/linux/blob/v6.14/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c#L2572 <https://github.com/torvalds/linux/blob/v6.14/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c#L2572>
> >
> > This patch is skip amdgpu_amdkfd_resume_process() call in thaw() during
> > hibernation. it is not skipped in restore() during resume from
> > hibernation when system boot again.
> >
> >
> > I just found the following kernel doc. Thaw() is intended to resume the
> > storage device for saving the hibernation image.
>
> Ah, that makes much more sense.
>
> > Our GPU is not involved
> > in it, it is not necessary to resume our GPU in thaw().
> > https://github.com/torvalds/linux/blob/v6.14/Documentation/power/pci.rst?plain=1#L588 <https://github.com/torvalds/linux/blob/v6.14/Documentation/power/pci.rst?plain=1#L588>
> >
> > So another implementation is to remove the amdgpu_device_resume() call
> > in amdgpu_pmops_thaw(), and skip amdgpu_device_ip_suspend() call in
> > amdgpu_pci_shutdown()for hibernation.
> > Initial tests show it's working fine for hibernation successful case.
> > Should I switch to this implementation?
>
> No idea. Alex and the KFD guys need to take a look at that.
>
> > But thaw() is also called to restore the GPU when hibernation is aborted
> > due to some error in hibernation image creation stage. In this case,
> > amdgpu_device_resume() is needed in thaw().
> >
> > So I need a method to check if hibernation is aborted or not to
> > conditionally skip amdgpu_device_resume() in thaw(). Currently I don't
> > know how to do this.
>
> Yeah that approach here looks fishy to me, but I don't know how to properly fix it either.
>
> @Alex any idea?

Yeah, I'm not sure how to handle that.  I don't see a way to avoid
having all of the callbacks.  We could ideally skip some of the steps.
Maybe we could optimize the freeze and thaw routines if we had some
hint from the pm core about why we were getting called.  E.g., thaw
after a failed hibernation restore.

Alex

>
> Regards,
> Christian.
>
> >
> >
> > Regards
> > Sam
> >
> >
> > On 2025/6/30 19:58, Christian König wrote:
> >> On 30.06.25 12:41, Samuel Zhang wrote:
> >>> The hibernation successful workflow:
> >>> - prepare: evict VRAM and swapout GTT BOs
> >>> - freeze
> >>> - create the hibernation image in system memory
> >>> - thaw: swapin and restore BOs
> >> Why should a thaw happen here in between?
> >>
> >>> - complete
> >>> - write hibernation image to disk
> >>> - amdgpu_pci_shutdown
> >>> - goto S5, turn off the system.
> >>>
> >>> During prepare stage of hibernation, VRAM and GTT BOs will be swapout to
> >>> shmem. Then in thaw stage, all BOs will be swapin and restored.
> >> That's not correct. This is done by the application starting again and not during thaw.
> >>
> >>> On server with 192GB VRAM * 8 dGPUs and 1.7TB system memory,
> >>> the swapin and restore BOs takes too long (50 minutes) and it is not
> >>> necessary since the follow-up stages does not use GPU.
> >>>
> >>> This patch is to skip BOs restore during thaw to reduce the hibernation
> >>> time.
> >> As far as I can see that doesn't make sense. The KFD processes need to be resumed here and that can't be skipped.
> >>
> >> Regards,
> >> Christian.
> >>
> >>> Signed-off-by: Samuel Zhang <guoqing.zhang at amd.com>
> >>> ---
> >>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
> >>>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 2 ++
> >>>   2 files changed, 3 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >>> index a8f4697deb1b..b550d07190a2 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >>> @@ -5328,7 +5328,7 @@ int amdgpu_device_resume(struct drm_device *dev, bool notify_clients)
> >>>               amdgpu_virt_init_data_exchange(adev);
> >>>               amdgpu_virt_release_full_gpu(adev, true);
> >>>
> >>> -            if (!adev->in_s0ix && !r && !adev->in_runpm)
> >>> +            if (!adev->in_s0ix && !r && !adev->in_runpm && !adev->in_s4)
> >>>                       r = amdgpu_amdkfd_resume_process(adev);
> >>>       }
> >>>
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >>> index 571b70da4562..23b76e8ac2fd 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >>> @@ -2734,7 +2734,9 @@ static int amdgpu_pmops_poweroff(struct device *dev)
> >>>   static int amdgpu_pmops_restore(struct device *dev)
> >>>   {
> >>>       struct drm_device *drm_dev = dev_get_drvdata(dev);
> >>> +    struct amdgpu_device *adev = drm_to_adev(drm_dev);
> >>>
> >>> +    adev->in_s4 = false;
> >>>       return amdgpu_device_resume(drm_dev, true);
> >>>   }
> >>>
> >
>