[PATCH] drm/amd/display: Fix deadlock during gpu reset v2

[Chen, Guchun]

[AMD Public Use]

When using dc_allow_idle_optimizations, should it be guarded by CONFIG_DRM_AMD_DC_DCN?

Regards,
Guchun

-----Original Message-----
From: Bhawanpreet Lakha <Bhawanpreet.Lakha at amd.com> 
Sent: Tuesday, January 12, 2021 5:03 AM
To: Kazlauskas, Nicholas <Nicholas.Kazlauskas at amd.com>; Chen, Guchun <Guchun.Chen at amd.com>; Deucher, Alexander <Alexander.Deucher at amd.com>
Cc: amd-gfx at lists.freedesktop.org; Lakha, Bhawanpreet <Bhawanpreet.Lakha at amd.com>
Subject: [PATCH] drm/amd/display: Fix deadlock during gpu reset v2

[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:
 - disable idle optimizations and skip calls to the dc function

v2: skip idle optimizations calls

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, 6 insertions(+)

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..858c6ff173ba 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -1816,6 +1816,9 @@ static int dm_suspend(void *handle)
 
 	if (amdgpu_in_reset(adev)) {
 		mutex_lock(&dm->dc_lock);
+
+		dc_allow_idle_optimizations(adev->dm.dc, false);
+
 		dm->cached_dc_state = dc_copy_state(dm->dc->current_state);
 
 		dm_gpureset_toggle_interrupts(adev, dm->cached_dc_state, false); @@ -5556,6 +5559,9 @@ static inline int dm_set_vblank(struct drm_crtc *crtc, bool enable)
 	if (!dc_interrupt_set(adev->dm.dc, irq_source, enable))
 		return -EBUSY;
 
+	if (amdgpu_in_reset(adev))
+		return 0;
+
 	mutex_lock(&dm->dc_lock);
 
 	if (enable)
--
2.25.1