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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hersen Wu <hersenwu@amd.com>,
        Jasdeep Dhillon <jdhillon@amd.com>,
        Roman Li <Roman.Li@amd.com>,
        Daniel Wheeler <daniel.wheeler@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.16 0502/1017] drm/amd/display: Add affected crtcs to atomic state for dsc mst unplug
Date:   Tue,  5 Apr 2022 09:23:35 +0200
Message-Id: <20220405070409.200254124@linuxfoundation.org>
In-Reply-To: <20220405070354.155796697@linuxfoundation.org>
References: <20220405070354.155796697@linuxfoundation.org>
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From: Roman Li <Roman.Li@amd.com>

[ Upstream commit 128f8ed5902a287a6bb4afe0ffdae8a80b2a64ec ]

[Why]
When display topology changed on DSC hub we add all crtcs with dsc support to
atomic state.
Refer to patch:"drm/amd/display: Trigger modesets on MST DSC connectors"
However the original implementation may skip crtc if the topology change
caused by unplug.
That potentially could lead to no-lightup or corruption on DSC hub after
unplug event on one of the connectors.

[How]
Update add_affected_mst_dsc_crtcs() to use old connector state
if new connector state has no crtc (undergoes modeset due to unplug)

Fixes: 44be939ff7ac58 ("drm/amd/display: Trigger modesets on MST DSC connectors")

Reviewed-by: Hersen Wu <hersenwu@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 7 +++++--
 1 file changed, 5 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 0ec8051cdfb4..7cadb9e81d9d 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -10752,10 +10752,13 @@ static int dm_check_crtc_cursor(struct drm_atomic_state *state,
 static int add_affected_mst_dsc_crtcs(struct drm_atomic_state *state, struct drm_crtc *crtc)
 {
 	struct drm_connector *connector;
-	struct drm_connector_state *conn_state;
+	struct drm_connector_state *conn_state, *old_conn_state;
 	struct amdgpu_dm_connector *aconnector = NULL;
 	int i;
-	for_each_new_connector_in_state(state, connector, conn_state, i) {
+	for_each_oldnew_connector_in_state(state, connector, old_conn_state, conn_state, i) {
+		if (!conn_state->crtc)
+			conn_state = old_conn_state;
+
 		if (conn_state->crtc != crtc)
 			continue;
 
-- 
2.34.1