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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