linux-kernel - [PATCH 1/3] drm/amdgpu/dm/mst: Stop grabbing mst_mgr->lock in compute_mst_dsc_configs_for

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Date:   Thu,  2 Jun 2022 17:00:54 -0400
From:   Lyude Paul <lyude@...hat.com>
To:     amd-gfx@...edesktop.org
Cc:     Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Hersen Wu <hersenwu@....com>,
        Roman Li <Roman.Li@....com>, Fangzhi Zuo <Jerry.Zuo@....com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        amd-gfx@...ts.freedesktop.org (open list:AMD DISPLAY CORE),
        dri-devel@...ts.freedesktop.org (open list:DRM DRIVERS),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/3] drm/amdgpu/dm/mst: Stop grabbing mst_mgr->lock in compute_mst_dsc_configs_for_state()

Noticed this while trying to update amdgpu for the non-atomic MST removal
changes - for some reason we appear to grab mst_mgr->lock before computing
mst DSC configs. This is wrong though - mst_mgr->lock is only needed while
traversing the actual MST topology state - which is not typically something
that DRM drivers should be doing themselves anyway.

Signed-off-by: Lyude Paul <lyude@...hat.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 9221b6690a4a..cb3b0e08acc4 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -1056,13 +1056,10 @@ bool compute_mst_dsc_configs_for_state(struct drm_atomic_state *state,
 		if (!is_dsc_need_re_compute(state, dc_state, stream->link))
 			continue;
 
-		mutex_lock(&aconnector->mst_mgr.lock);
 		if (!compute_mst_dsc_configs_for_link(state, dc_state, stream->link,
 			vars, &link_vars_start_index)) {
-			mutex_unlock(&aconnector->mst_mgr.lock);
 			return false;
 		}
-		mutex_unlock(&aconnector->mst_mgr.lock);
 
 		for (j = 0; j < dc_state->stream_count; j++) {
 			if (dc_state->streams[j]->link == stream->link)
-- 
2.35.3