RE: [PATCH 1/2] drm/amdgpu: Use mod_delayed_work in amdgpu_gfx_off_ctrl

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

[AMD Official Use Only]

Reviewed-by: Evan Quan <evan.quan@amd.com>

> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of
> Michel Dänzer
> Sent: Thursday, August 12, 2021 12:52 AM
> To: Deucher, Alexander <Alexander.Deucher@amd.com>; Koenig, Christian
> <Christian.Koenig@amd.com>
> Cc: Liu, Leo <Leo.Liu@amd.com>; Zhu, James <James.Zhu@amd.com>; amd-
> gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org
> Subject: [PATCH 1/2] drm/amdgpu: Use mod_delayed_work in
> amdgpu_gfx_off_ctrl
> 
> From: Michel Dänzer <mdaenzer@redhat.com>
> 
> In contrast to schedule_delayed_work, this pushes back the work if it
> was already scheduled before. Specific behaviour change:
> 
> Before:
> 
> amdgpu_device_delay_enable_gfx_off ran ~100 ms after the first time
> GFXOFF was disabled and re-enabled, even if GFXOFF was disabled and
> re-enabled again during those 100 ms.
> 
> After:
> 
> amdgpu_device_delay_enable_gfx_off runs ~100 ms after the last time
> GFXOFF is disabled and re-enabled.
> 
> The former resulted in frame drops / stutter with the upcoming mutter
> 41 release on Navi 14, due to constantly enabling GFXOFF in the HW and
> disabling it again (for getting the GPU clock counter).
> 
> Signed-off-by: Michel Dänzer <mdaenzer@redhat.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> index a0be0772c8b3..9cfef56b2aee 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> @@ -569,7 +569,7 @@ void amdgpu_gfx_off_ctrl(struct amdgpu_device
> *adev, bool enable)
>  		adev->gfx.gfx_off_req_count--;
> 
>  	if (enable && !adev->gfx.gfx_off_state && !adev-
> >gfx.gfx_off_req_count) {
> -		schedule_delayed_work(&adev->gfx.gfx_off_delay_work,
> GFX_OFF_DELAY_ENABLE);
> +		mod_delayed_work(system_wq, &adev-
> >gfx.gfx_off_delay_work, GFX_OFF_DELAY_ENABLE);
>  	} else if (!enable && adev->gfx.gfx_off_state) {
>  		if (!amdgpu_dpm_set_powergating_by_smu(adev,
> AMD_IP_BLOCK_TYPE_GFX, false)) {
>  			adev->gfx.gfx_off_state = false;
> --
> 2.32.0