[AMD Official Use Only - Internal Distribution Only]
right, that makes more sense. I will post a v2 shortly
________________________________
From: Kazlauskas, Nicholas <nicholas.kazlaus...@amd.com>
Sent: January 11, 2021 3:22 PM
To: Lakha, Bhawanpreet <bhawanpreet.la...@amd.com>; Chen, Guchun
<guchun.c...@amd.com>; Deucher, Alexander <alexander.deuc...@amd.com>
Cc: amd-gfx@lists.freedesktop.org <amd-gfx@lists.freedesktop.org>
Subject: Re: [PATCH] drm/amd/display: Fix deadlock during gpu reset
On 2021-01-11 2:55 p.m., Bhawanpreet Lakha wrote:
> [Why]
> during idle optimizations we acquire the dc_lock, this lock is also
> acquired during gpu_reset so we end up hanging the system due to a
> deadlock
>
> [How]
> If we are in gpu reset dont acquire the dc lock, as we already have it
Are we sure this is the behavior we want?
I think if we are in GPU reset then we shouldn't be attempting to modify
idle optimization state at all, ie. return early if amdgpu_in_reset.
The calls around the locks are working around bad policy.
Regards,
Nicholas Kazlauskas
>
> Fixes: 06d5652541c3 ("drm/amd/display: enable idle optimizations for linux
> (MALL stutter)")
> Signed-off-by: Bhawanpreet Lakha <bhawanpreet.la...@amd.com>
> ---
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 99c7f9eb44aa..2170e1b2d32c 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -5556,7 +5556,8 @@ static inline int dm_set_vblank(struct drm_crtc *crtc,
> bool enable)
> if (!dc_interrupt_set(adev->dm.dc, irq_source, enable))
> return -EBUSY;
>
> - mutex_lock(&dm->dc_lock);
> + if (!amdgpu_in_reset(adev))
> + mutex_lock(&dm->dc_lock);
>
> if (enable)
> dm->active_vblank_irq_count++;
> @@ -5568,7 +5569,8 @@ static inline int dm_set_vblank(struct drm_crtc *crtc,
> bool enable)
>
> DRM_DEBUG_DRIVER("Allow idle optimizations (MALL): %d\n",
> dm->active_vblank_irq_count == 0);
>
> - mutex_unlock(&dm->dc_lock);
> + if (!amdgpu_in_reset(adev))
> + mutex_unlock(&dm->dc_lock);
>
> return 0;
> }
>
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