drm: Add drm_plane/connector_index

In the atomic state we'll have an array of states for crtcs, planes
and connectors and need to be able to at them by their index. We
already have a drm_crtc_index function so add the missing ones for
planes and connectors.

If it later on turns out that the list walking is too expensive we can
add the index to the relevant modeset objects.

Rob Clark doesn't like the loops too much, but we can always add an
obj->idx parameter later on. And for now reiterating is actually safer
since nowadays we have hotpluggable connectors (thanks to DP MST).

v2: Fix embarrassing copypasta fail in kerneldoc and header
declarations, spotted by Matt Roper.

Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -1021,6 +1021,29 @@ void drm_connector_cleanup(struct drm_connector *connector)
 }
 EXPORT_SYMBOL(drm_connector_cleanup);
 
+/**
+ * drm_connector_index - find the index of a registered connector
+ * @connector: connector to find index for
+ *
+ * Given a registered connector, return the index of that connector within a DRM
+ * device's list of connectors.
+ */
+unsigned int drm_connector_index(struct drm_connector *connector)
+{
+	unsigned int index = 0;
+	struct drm_connector *tmp;
+
+	list_for_each_entry(tmp, &connector->dev->mode_config.connector_list, head) {
+		if (tmp == connector)
+			return index;
+
+		index++;
+	}
+
+	BUG();
+}
+EXPORT_SYMBOL(drm_connector_index);
+
 /**
  * drm_connector_register - register a connector
  * @connector: the connector to register
@@ -1325,6 +1348,29 @@ void drm_plane_cleanup(struct drm_plane *plane)
 }
 EXPORT_SYMBOL(drm_plane_cleanup);
 
+/**
+ * drm_plane_index - find the index of a registered plane
+ * @plane: plane to find index for
+ *
+ * Given a registered plane, return the index of that CRTC within a DRM
+ * device's list of planes.
+ */
+unsigned int drm_plane_index(struct drm_plane *plane)
+{
+	unsigned int index = 0;
+	struct drm_plane *tmp;
+
+	list_for_each_entry(tmp, &plane->dev->mode_config.plane_list, head) {
+		if (tmp == plane)
+			return index;
+
+		index++;
+	}
+
+	BUG();
+}
+EXPORT_SYMBOL(drm_plane_index);
+
 /**
  * drm_plane_force_disable - Forcibly disable a plane
  * @plane: plane to disable

include/drm/drm_crtc.h

@@ -904,6 +904,7 @@ int drm_connector_register(struct drm_connector *connector);
 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 */
 extern void drm_connector_unplug_all(struct drm_device *dev);
 
@@ -943,6 +944,7 @@ extern int drm_plane_init(struct drm_device *dev,
 			  const uint32_t *formats, uint32_t format_count,
 			  bool is_primary);
 extern void drm_plane_cleanup(struct drm_plane *plane);
+extern unsigned int drm_plane_index(struct drm_plane *plane);
 extern void drm_plane_force_disable(struct drm_plane *plane);
 extern int drm_crtc_check_viewport(const struct drm_crtc *crtc,
 				   int x, int y,