drm/msm/dp: support setting the DP subconnector type

Read the downstream port info and set the subconnector type accordingly.

Signed-off-by: Dmitry Baryshkov <[e-mail]>
Reviewed-by: Stephen Boyd <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/555531/
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/msm/dp/dp_display.c

···
 	}
 
 	/* reset video pattern flag on disconnect */
-	if (!hpd)
+	if (!hpd) {
 		dp->panel->video_test = false;
+		drm_dp_set_subconnector_property(dp->dp_display.connector,
+						 connector_status_disconnected,
+						 dp->panel->dpcd, dp->panel->downstream_ports);
+	}
 
 	dp->dp_display.is_connected = hpd;
 
···
 		goto end;
 
 	dp_link_process_request(dp->link);
+
+	drm_dp_set_subconnector_property(dp->dp_display.connector, connector_status_connected,
+					 dp->panel->dpcd, dp->panel->downstream_ports);
 
 	edid = dp->panel->edid;
 

drivers/gpu/drm/msm/dp/dp_panel.c

···
 		}
 	}
 
+	rc = drm_dp_read_downstream_info(panel->aux, dp_panel->dpcd,
+					 dp_panel->downstream_ports);
+	if (rc)
+		return rc;
+
 	kfree(dp_panel->edid);
 	dp_panel->edid = NULL;
 

drivers/gpu/drm/msm/dp/dp_panel.h

···
 struct dp_panel {
 	/* dpcd raw data */
 	u8 dpcd[DP_RECEIVER_CAP_SIZE];
+	u8 downstream_ports[DP_MAX_DOWNSTREAM_PORTS];
 
 	struct dp_link_info link_info;
 	struct drm_dp_desc desc;