drm/radeon: Don't turn off DP sink when disconnected

[ Upstream commit a3f73c8cf43858455a979d0f8354815e1443c496 ]

Turning off the sink in this case causes various issues, because
userspace expects it to stay on until it turns it off explicitly.

Instead, turn the sink off and back on when a display is connected
again. This dance seems necessary for link training to work correctly.

Bugzilla: https://bugs.freedesktop.org/105308
Cc: stable@vger.kernel.org
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>

diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index 9f699e87320a9cc5c7eedd3b7f84188e05e7fa37..6806772f3647d4b3960e87f1f47ffe7bb2374d62 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -89,25 +89,18 @@ void radeon_connector_hotplug(struct drm_connector *connector)
                /* don't do anything if sink is not display port, i.e.,
                 * passive dp->(dvi|hdmi) adaptor
                 */
-               if (dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT) {
-                       int saved_dpms = connector->dpms;
-                       /* Only turn off the display if it's physically disconnected */
-                       if (!radeon_hpd_sense(rdev, radeon_connector->hpd.hpd)) {
-                               drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF);
-                       } else if (radeon_dp_needs_link_train(radeon_connector)) {
-                               /* Don't try to start link training before we
-                                * have the dpcd */
-                               if (!radeon_dp_getdpcd(radeon_connector))
-                                       return;
-
-                               /* set it to OFF so that drm_helper_connector_dpms()
-                                * won't return immediately since the current state
-                                * is ON at this point.
-                                */
-                               connector->dpms = DRM_MODE_DPMS_OFF;
-                               drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON);
-                       }
-                       connector->dpms = saved_dpms;
+               if (dig_connector->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT &&
+                   radeon_hpd_sense(rdev, radeon_connector->hpd.hpd) &&
+                   radeon_dp_needs_link_train(radeon_connector)) {
+                       /* Don't start link training before we have the DPCD */
+                       if (!radeon_dp_getdpcd(radeon_connector))
+                               return;
+
+                       /* Turn the connector off and back on immediately, which
+                        * will trigger link training
+                        */
+                       drm_helper_connector_dpms(connector, DRM_MODE_DPMS_OFF);
+                       drm_helper_connector_dpms(connector, DRM_MODE_DPMS_ON);
                }
        }
 }