drm/radeon: Properly handle DDC probe for DP bridges

DDC information can be accessed using AUX CH

Fixes failure to probe monitors on some systems with
DP bridge chips.

agd5f: minor fixes
Signed-off-by: Niels Ole Salscheider <niels_ole@salscheider-online.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/radeon_connectors.c

@@ -741,7 +741,7 @@ radeon_vga_detect(struct drm_connector *connector, bool force)
 		ret = connector_status_disconnected;
 
 	if (radeon_connector->ddc_bus)
-		dret = radeon_ddc_probe(radeon_connector);
+		dret = radeon_ddc_probe(radeon_connector, false);
 	if (dret) {
 		radeon_connector->detected_by_load = false;
 		if (radeon_connector->edid) {
@@ -947,7 +947,7 @@ radeon_dvi_detect(struct drm_connector *connector, bool force)
 		return connector->status;
 
 	if (radeon_connector->ddc_bus)
-		dret = radeon_ddc_probe(radeon_connector);
+		dret = radeon_ddc_probe(radeon_connector, false);
 	if (dret) {
 		radeon_connector->detected_by_load = false;
 		if (radeon_connector->edid) {
@@ -1401,7 +1401,8 @@ radeon_dp_detect(struct drm_connector *connector, bool force)
 		if (encoder) {
 			/* setup ddc on the bridge */
 			radeon_atom_ext_encoder_setup_ddc(encoder);
-			if (radeon_ddc_probe(radeon_connector)) /* try DDC */
+			/* bridge chips are always aux */
+			if (radeon_ddc_probe(radeon_connector, true)) /* try DDC */
 				ret = connector_status_connected;
 			else if (radeon_connector->dac_load_detect) { /* try load detection */
 				struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
@@ -1419,7 +1420,8 @@ radeon_dp_detect(struct drm_connector *connector, bool force)
 				if (radeon_dp_getdpcd(radeon_connector))
 					ret = connector_status_connected;
 			} else {
-				if (radeon_ddc_probe(radeon_connector))
+				/* try non-aux ddc (DP to DVI/HMDI/etc. adapter) */
+				if (radeon_ddc_probe(radeon_connector, false))
 					ret = connector_status_connected;
 			}
 		}

drivers/gpu/drm/radeon/radeon_display.c

@@ -699,10 +699,15 @@ int radeon_ddc_get_modes(struct radeon_connector *radeon_connector)
 	if (radeon_connector->router.ddc_valid)
 		radeon_router_select_ddc_port(radeon_connector);
 
-	if ((radeon_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) ||
-	    (radeon_connector->base.connector_type == DRM_MODE_CONNECTOR_eDP) ||
-	    (radeon_connector_encoder_get_dp_bridge_encoder_id(&radeon_connector->base) !=
-	     ENCODER_OBJECT_ID_NONE)) {
+	if (radeon_connector_encoder_get_dp_bridge_encoder_id(&radeon_connector->base) !=
+	    ENCODER_OBJECT_ID_NONE) {
+		struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
+
+		if (dig->dp_i2c_bus)
+			radeon_connector->edid = drm_get_edid(&radeon_connector->base,
+							      &dig->dp_i2c_bus->adapter);
+	} else if ((radeon_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) ||
+		   (radeon_connector->base.connector_type == DRM_MODE_CONNECTOR_eDP)) {
 		struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
 
 		if ((dig->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT ||

drivers/gpu/drm/radeon/radeon_i2c.c

@@ -39,7 +39,7 @@ extern u32 radeon_atom_hw_i2c_func(struct i2c_adapter *adap);
  * radeon_ddc_probe
  *
  */
-bool radeon_ddc_probe(struct radeon_connector *radeon_connector)
+bool radeon_ddc_probe(struct radeon_connector *radeon_connector, bool use_aux)
 {
 	u8 out = 0x0;
 	u8 buf[8];
@@ -63,7 +63,13 @@ bool radeon_ddc_probe(struct radeon_connector *radeon_connector)
 	if (radeon_connector->router.ddc_valid)
 		radeon_router_select_ddc_port(radeon_connector);
 
+	if (use_aux) {
+		struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
+		ret = i2c_transfer(&dig->dp_i2c_bus->adapter, msgs, 2);
+	} else {
 		ret = i2c_transfer(&radeon_connector->ddc_bus->adapter, msgs, 2);
+	}
+
 	if (ret != 2)
 		/* Couldn't find an accessible DDC on this connector */
 		return false;

drivers/gpu/drm/radeon/radeon_mode.h

@@ -559,7 +559,7 @@ extern void radeon_i2c_put_byte(struct radeon_i2c_chan *i2c,
 				u8 val);
 extern void radeon_router_select_ddc_port(struct radeon_connector *radeon_connector);
 extern void radeon_router_select_cd_port(struct radeon_connector *radeon_connector);
-extern bool radeon_ddc_probe(struct radeon_connector *radeon_connector);
+extern bool radeon_ddc_probe(struct radeon_connector *radeon_connector, bool use_aux);
 extern int radeon_ddc_get_modes(struct radeon_connector *radeon_connector);
 
 extern struct drm_encoder *radeon_best_encoder(struct drm_connector *connector);