[PATCH 1/3] drm: introduce drm_connector_plug_all() helper

[Alexey Brodkin <Alexey.Brodkin@synopsys.com>]

As a pair to already existing drm_connector_unplug_all() we're adding
generic implementation of what is already done in some drivers.

Once this helper is implemented we'll be ready to switch existing
driver-specific implementations with generic one.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
---
 drivers/gpu/drm/drm_crtc.c | 44 +++++++++++++++++++++++++++++++++++++++++++-
 drivers/gpu/drm/drm_drv.c  |  3 ++-
 include/drm/drm_crtc.h     |  3 ++-
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 65258ac..ce27420 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -1080,6 +1080,46 @@ void drm_connector_unregister(struct drm_connector *connector)
 }
 EXPORT_SYMBOL(drm_connector_unregister);
 
+/**
+ * drm_connector_plug_all - register connector userspace interfaces
+ * @dev: drm device
+ *
+ * This function registers all connector userspace interfaces in sysfs. Should
+ * be call when the device is disconnected, e.g. from an usb driver's
+ * ->connect callback.
+ */
+int drm_connector_plug_all(struct drm_device *dev)
+{
+	struct drm_connector *connector, *failed;
+	int ret;
+
+	mutex_lock(&dev->mode_config.mutex);
+
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		ret = drm_connector_register(connector);
+		if (ret) {
+			failed = connector;
+			goto err;
+		}
+	}
+
+	mutex_unlock(&dev->mode_config.mutex);
+
+	return 0;
+
+err:
+	list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
+		if (failed == connector)
+			break;
+
+		drm_connector_unregister(connector);
+	}
+
+	mutex_unlock(&dev->mode_config.mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_connector_plug_all);
 
 /**
  * drm_connector_unplug_all - unregister connector userspace interfaces
@@ -1093,10 +1133,12 @@ void drm_connector_unplug_all(struct drm_device *dev)
 {
 	struct drm_connector *connector;
 
-	/* FIXME: taking the mode config mutex ends up in a clash with sysfs */
+	mutex_lock(&dev->mode_config.mutex);
+
 	list_for_each_entry(connector, &dev->mode_config.connector_list, head)
 		drm_connector_unregister(connector);
 
+	mutex_unlock(&dev->mode_config.mutex);
 }
 EXPORT_SYMBOL(drm_connector_unplug_all);
 
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 167c8d3..4a559c6 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -715,7 +715,8 @@ EXPORT_SYMBOL(drm_dev_unref);
  *
  * Register the DRM device @dev with the system, advertise device to user-space
  * and start normal device operation. @dev must be allocated via drm_dev_alloc()
- * previously.
+ * previously and right after drm_dev_register() driver should call
+ * drm_connector_plug_all() to register all connectors in sysfs.
  *
  * Never call this twice on any device!
  *
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 8c7fb3d..aa8789e 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -2214,7 +2214,8 @@ void drm_connector_unregister(struct drm_connector *connector);
 
 extern void drm_connector_cleanup(struct drm_connector *connector);
 extern unsigned int drm_connector_index(struct drm_connector *connector);
-/* helper to unplug all connectors from sysfs for device */
+/* helpers to plug/unplug all connectors to/from sysfs for device */
+extern int drm_connector_plug_all(struct drm_device *dev);
 extern void drm_connector_unplug_all(struct drm_device *dev);
 
 extern int drm_bridge_add(struct drm_bridge *bridge);
-- 
2.5.0