[PATCH] drm/amd/display: Fix deadlock during gpu reset

[Bhawanpreet Lakha]

[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

Fixes: 06d5652541c3 ("drm/amd/display: enable idle optimizations for linux (MALL stutter)")
Signed-off-by: Bhawanpreet Lakha <Bhawanpreet.Lakha at 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;
 }
-- 
2.25.1