From 128f8ed5902a287a6bb4afe0ffdae8a80b2a64ec Mon Sep 17 00:00:00 2001
From: Roman Li <Roman.Li@amd.com>
Date: Thu, 23 Dec 2021 17:39:57 -0500
Subject: [PATCH] drm/amd/display: Add affected crtcs to atomic state for dsc mst unplug
Git-commit: 128f8ed5902a287a6bb4afe0ffdae8a80b2a64ec
Patch-mainline: v5.18-rc1
References: git-fixes

[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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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 be4852757818..e496bedc1a7a 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -10851,10 +10851,13 @@ 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;
 
-- 
2.31.1