drm: add of_graph endpoint helper to find possible CRTCs

Add a helper to allow encoders to find their possible CRTCs from the
OF graph without having to re-implement this functionality.  We add a
device_node to drm_crtc which corresponds with the port node in the
DT description of the CRTC device.

We can then scan the DRM device list for CRTCs to find their index,
matching the appropriate CRTC using the port device_node, thus building
up the possible CRTC mask.

Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 251b75e6bf7a..6a94909f1ca9 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -41,6 +41,7 @@ struct drm_framebuffer;
 struct drm_object_properties;
 struct drm_file;
 struct drm_clip_rect;
+struct device_node;
 
 #define DRM_MODE_OBJECT_CRTC 0xcccccccc
 #define DRM_MODE_OBJECT_CONNECTOR 0xc0c0c0c0
@@ -314,6 +315,7 @@ struct drm_crtc_funcs {
  */
 struct drm_crtc {
         struct drm_device *dev;
+        struct device_node *port;
         struct list_head head;
 
         /**