drm/radeon/kms: fix quirk for MSI laptop

The line mux for the connector in the bios tables
is used for enumerating drm connectors.  Since
this laptop has a quirk where the same line much is
listed for both VGA and LVDS, the connectors get
combined.  Setting the line mux on LVDS to an unused
value prevents both encoders from being combined into
the same connector.  This should fix bko bug 13720.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -103,7 +103,8 @@ static inline struct radeon_i2c_bus_rec radeon_lookup_gpio(struct drm_device
 static bool radeon_atom_apply_quirks(struct drm_device *dev,
 				     uint32_t supported_device,
 				     int *connector_type,
-				     struct radeon_i2c_bus_rec *i2c_bus)
+				     struct radeon_i2c_bus_rec *i2c_bus,
+				     uint8_t *line_mux)
 {
 
 	/* Asus M2A-VM HDMI board lists the DVI port as HDMI */
@@ -127,8 +128,10 @@ static bool radeon_atom_apply_quirks(struct drm_device *dev,
 	if ((dev->pdev->device == 0x5653) &&
 	    (dev->pdev->subsystem_vendor == 0x1462) &&
 	    (dev->pdev->subsystem_device == 0x0291)) {
-		if (*connector_type == DRM_MODE_CONNECTOR_LVDS)
+		if (*connector_type == DRM_MODE_CONNECTOR_LVDS) {
 			i2c_bus->valid = false;
+			*line_mux = 53;
+		}
 	}
 
 	/* Funky macbooks */
@@ -526,7 +529,7 @@ bool radeon_get_atom_connector_info_from_supported_devices_table(struct
 
 		if (!radeon_atom_apply_quirks
 		    (dev, (1 << i), &bios_connectors[i].connector_type,
-		     &bios_connectors[i].ddc_bus))
+		     &bios_connectors[i].ddc_bus, &bios_connectors[i].line_mux))
 			continue;
 
 		bios_connectors[i].valid = true;