[AMD Official Use Only]
Thanks! This seems fine to me.
Reviewed-by: Evan Quan <evan.q...@amd.com>
> -----Original Message-----
> From: amd-gfx <amd-gfx-boun...@lists.freedesktop.org> On Behalf Of
> Michel Dänzer
> Sent: Tuesday, August 17, 2021 4:23 PM
> To: Deucher, Alexander <alexander.deuc...@amd.com>; Koenig, Christian
> <christian.koe...@amd.com>
> Cc: Liu, Leo <leo....@amd.com>; Zhu, James <james....@amd.com>; amd-
> g...@lists.freedesktop.org; dri-de...@lists.freedesktop.org
> Subject: [PATCH] drm/amdgpu: Cancel delayed work when GFXOFF is
> disabled
>
> From: Michel Dänzer <mdaen...@redhat.com>
>
> schedule_delayed_work does not push back the work if it was already
> scheduled before, so 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.
>
> This 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).
>
> To fix this, call cancel_delayed_work_sync when the disable count transitions
> from 0 to 1, and only schedule the delayed work on the reverse transition,
> not if the disable count was already 0. This makes sure the delayed work
> doesn't run at unexpected times, and allows it to be lock-free.
>
> v2:
> * Use cancel_delayed_work_sync & mutex_trylock instead of
> mod_delayed_work.
> v3:
> * Make amdgpu_device_delay_enable_gfx_off lock-free (Christian König)
> v4:
> * Fix race condition between amdgpu_gfx_off_ctrl incrementing
> adev->gfx.gfx_off_req_count and amdgpu_device_delay_enable_gfx_off
> checking for it to be 0 (Evan Quan)
>
> Cc: sta...@vger.kernel.org
> Reviewed-by: Lijo Lazar <lijo.la...@amd.com> # v3
> Acked-by: Christian König <christian.koe...@amd.com> # v3
> Signed-off-by: Michel Dänzer <mdaen...@redhat.com>
> ---
>
> Alex, probably best to wait a bit longer before picking this up. :)
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 11 +++----
> drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c | 36 +++++++++++++++----
> ---
> 2 files changed, 30 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index f3fd5ec710b6..f944ed858f3e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -2777,12 +2777,11 @@ static void
> amdgpu_device_delay_enable_gfx_off(struct work_struct *work)
> struct amdgpu_device *adev =
> container_of(work, struct amdgpu_device,
> gfx.gfx_off_delay_work.work);
>
> - mutex_lock(&adev->gfx.gfx_off_mutex);
> - if (!adev->gfx.gfx_off_state && !adev->gfx.gfx_off_req_count) {
> - if (!amdgpu_dpm_set_powergating_by_smu(adev,
> AMD_IP_BLOCK_TYPE_GFX, true))
> - adev->gfx.gfx_off_state = true;
> - }
> - mutex_unlock(&adev->gfx.gfx_off_mutex);
> + WARN_ON_ONCE(adev->gfx.gfx_off_state);
> + WARN_ON_ONCE(adev->gfx.gfx_off_req_count);
> +
> + if (!amdgpu_dpm_set_powergating_by_smu(adev,
> AMD_IP_BLOCK_TYPE_GFX, true))
> + adev->gfx.gfx_off_state = true;
> }
>
> /**
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> index a0be0772c8b3..b4ced45301be 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
> @@ -563,24 +563,38 @@ void amdgpu_gfx_off_ctrl(struct amdgpu_device
> *adev, bool enable)
>
> mutex_lock(&adev->gfx.gfx_off_mutex);
>
> - if (!enable)
> - adev->gfx.gfx_off_req_count++;
> - else if (adev->gfx.gfx_off_req_count > 0)
> + if (enable) {
> + /* If the count is already 0, it means there's an imbalance bug
> somewhere.
> + * Note that the bug may be in a different caller than the one
> which triggers the
> + * WARN_ON_ONCE.
> + */
> + if (WARN_ON_ONCE(adev->gfx.gfx_off_req_count == 0))
> + goto unlock;
> +
> 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);
> - } 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;
> + if (adev->gfx.gfx_off_req_count == 0 && !adev-
> >gfx.gfx_off_state)
> + schedule_delayed_work(&adev-
> >gfx.gfx_off_delay_work, GFX_OFF_DELAY_ENABLE);
> + } else {
> + if (adev->gfx.gfx_off_req_count == 0) {
> + cancel_delayed_work_sync(&adev-
> >gfx.gfx_off_delay_work);
> +
> + if (adev->gfx.gfx_off_state &&
> + !amdgpu_dpm_set_powergating_by_smu(adev,
> AMD_IP_BLOCK_TYPE_GFX, false)) {
> + adev->gfx.gfx_off_state = false;
>
> - if (adev->gfx.funcs->init_spm_golden) {
> - dev_dbg(adev->dev, "GFXOFF is disabled, re-
> init SPM golden settings\n");
> - amdgpu_gfx_init_spm_golden(adev);
> + if (adev->gfx.funcs->init_spm_golden) {
> + dev_dbg(adev->dev,
> + "GFXOFF is disabled, re-init
> SPM golden settings\n");
> + amdgpu_gfx_init_spm_golden(adev);
> + }
> }
> }
> +
> + adev->gfx.gfx_off_req_count++;
> }
>
> +unlock:
> mutex_unlock(&adev->gfx.gfx_off_mutex);
> }
>
> --
> 2.32.0
