Patch "drm/msm/dp: fix panel bridge attachment" has been added to the 5.17-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/msm/dp: fix panel bridge attachment

to the 5.17-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-msm-dp-fix-panel-bridge-attachment.patch
and it can be found in the queue-5.17 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c7d1fbf1af425951a5a382c6c2a171beab421a64
Author: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
Date:   Sat Feb 12 01:40:02 2022 +0300

    drm/msm/dp: fix panel bridge attachment
    
    [ Upstream commit 4d793a02c4967ab14d4ae5e86a51ee02ed78921a ]
    
    In commit 8a3b4c17f863 ("drm/msm/dp: employ bridge mechanism for display
    enable and disable") the DP driver received a drm_bridge instance, which
    is always attached to the encoder as a root bridge. However it conflicts
    with the panel_bridge support for eDP panels. The panel bridge attaches
    to the encoder before the "dp" bridge (DP driver's drm_bridge instance
    created in msm_dp_bridge_init()) has a chance to do so. Change
    panel bridge attachment to come after the "dp" bridge attachment (and to
    use it as a previous bridge).
    
    Fixes: 8a3b4c17f863 ("drm/msm/dp: employ bridge mechanism for display enable and disable")
    Cc: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
    Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
    Tested-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
    Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220211224006.1797846-2-dmitry.baryshkov@xxxxxxxxxx
    [db: fixed commit message according to Stephen's suggestions]
    Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/msm/dp/dp_drm.c b/drivers/gpu/drm/msm/dp/dp_drm.c
index d4d360d19eba..26ef41a4c1b6 100644
--- a/drivers/gpu/drm/msm/dp/dp_drm.c
+++ b/drivers/gpu/drm/msm/dp/dp_drm.c
@@ -169,16 +169,6 @@ struct drm_connector *dp_drm_connector_init(struct msm_dp *dp_display)
 
 	drm_connector_attach_encoder(connector, dp_display->encoder);
 
-	if (dp_display->panel_bridge) {
-		ret = drm_bridge_attach(dp_display->encoder,
-					dp_display->panel_bridge, NULL,
-					DRM_BRIDGE_ATTACH_NO_CONNECTOR);
-		if (ret < 0) {
-			DRM_ERROR("failed to attach panel bridge: %d\n", ret);
-			return ERR_PTR(ret);
-		}
-	}
-
 	return connector;
 }
 
@@ -246,5 +236,16 @@ struct drm_bridge *msm_dp_bridge_init(struct msm_dp *dp_display, struct drm_devi
 		return ERR_PTR(rc);
 	}
 
+	if (dp_display->panel_bridge) {
+		rc = drm_bridge_attach(dp_display->encoder,
+					dp_display->panel_bridge, bridge,
+					DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+		if (rc < 0) {
+			DRM_ERROR("failed to attach panel bridge: %d\n", rc);
+			drm_bridge_remove(bridge);
+			return ERR_PTR(rc);
+		}
+	}
+
 	return bridge;
 }