backend-drm: handle hotplug events per drm device

If Weston receives a hotplug event, it has to check if the hotplug device
actually belongs to the drm device before updating the heads of the device. The
hotplug event should only remove heads that belong to the device and must not
change heads of other devices.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>

libweston/backend-drm/drm.c

@@ -2422,9 +2422,10 @@ resources_has_connector(drmModeRes *resources, uint32_t connector_id)
 }
 
 static void
-drm_backend_update_connectors(struct drm_backend *b, struct udev_device *drm_device)
+drm_backend_update_connectors(struct drm_device *device,
+			      struct udev_device *drm_device)
 {
-	struct drm_device *device = b->drm;
+	struct drm_backend *b = device->backend;
 	drmModeRes *resources;
 	drmModeConnector *conn;
 	struct weston_head *base, *base_next;
@@ -2472,6 +2473,9 @@ drm_backend_update_connectors(struct drm_backend *b, struct udev_device *drm_dev
 		head = to_drm_head(base);
 		connector_id = head->connector.connector_id;
 
+		if (head->connector.device != device)
+			continue;
+
 		if (resources_has_connector(resources, connector_id))
 			continue;
 
@@ -2544,9 +2548,8 @@ drm_backend_update_conn_props(struct drm_backend *b,
 }
 
 static int
-udev_event_is_hotplug(struct drm_backend *b, struct udev_device *udev_device)
+udev_event_is_hotplug(struct drm_device *device, struct udev_device *udev_device)
 {
-	struct drm_device *device = b->drm;
 	const char *sysnum;
 	const char *val;
 
@@ -2595,11 +2598,11 @@ udev_drm_event(int fd, uint32_t mask, void *data)
 
 	event = udev_monitor_receive_device(b->udev_monitor);
 
-	if (udev_event_is_hotplug(b, event)) {
+	if (udev_event_is_hotplug(b->drm, event)) {
 		if (udev_event_is_conn_prop_change(b, event, &conn_id, &prop_id))
 			drm_backend_update_conn_props(b, conn_id, prop_id);
 		else
-			drm_backend_update_connectors(b, event);
+			drm_backend_update_connectors(b->drm, event);
 	}
 
 	udev_device_unref(event);