drm: bridge: Link encoder and bridge in core code

Instead of linking encoders and bridges in every driver (and getting it
wrong half of the time, as many drivers forget to set the drm_bridge
encoder pointer), do so in core code. The drm_bridge_attach() function
needs the encoder and optional previous bridge to perform that task,
update all the callers.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Stefan Agner <stefan@agner.ch> # For DCU
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com> # For atmel-hlcdc
Acked-by: Vincent Abriou <vincent.abriou@st.com> # For STI
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com> # For sun4i
Acked-by: Xinliang Liu <z.liuxinliang@hisilicon.com> # For hisilicon
Acked-by: Jyri Sarha <jsarha@ti.com> # For tilcdc
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1481709550-29226-4-git-send-email-laurent.pinchart+renesas@ideasonboard.com

1 files changed, 34 insertions, 12 deletions

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 0ee052b7c21a..850bd6509ef1 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -26,6 +26,7 @@
 #include <linux/mutex.h>
 
 #include <drm/drm_bridge.h>
+#include <drm/drm_encoder.h>
 
 /**
  * DOC: overview
@@ -92,32 +93,53 @@ void drm_bridge_remove(struct drm_bridge *bridge)
 EXPORT_SYMBOL(drm_bridge_remove);
 
 /**
- * drm_bridge_attach - associate given bridge to our DRM device
+ * drm_bridge_attach - attach the bridge to an encoder's chain
  *
- * @dev: DRM device
- * @bridge: bridge control structure
+ * @encoder: DRM encoder
+ * @bridge: bridge to attach
+ * @previous: previous bridge in the chain (optional)
  *
- * Called by a kms driver to link one of our encoder/bridge to the given
- * bridge.
+ * Called by a kms driver to link the bridge to an encoder's chain. The previous
+ * argument specifies the previous bridge in the chain. If NULL, the bridge is
+ * linked directly at the encoder's output. Otherwise it is linked at the
+ * previous bridge's output.
  *
- * Note that setting up links between the bridge and our encoder/bridge
- * objects needs to be handled by the kms driver itself.
+ * If non-NULL the previous bridge must be already attached by a call to this
+ * function.
  *
  * RETURNS:
  * Zero on success, error code on failure
  */
-int drm_bridge_attach(struct drm_device *dev, struct drm_bridge *bridge)
+int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
+		      struct drm_bridge *previous)
 {
-	if (!dev || !bridge)
+	int ret;
+
+	if (!encoder || !bridge)
+		return -EINVAL;
+
+	if (previous && (!previous->dev || previous->encoder != encoder))
 		return -EINVAL;
 
 	if (bridge->dev)
 		return -EBUSY;
 
-	bridge->dev = dev;
+	bridge->dev = encoder->dev;
+	bridge->encoder = encoder;
+
+	if (bridge->funcs->attach) {
+		ret = bridge->funcs->attach(bridge);
+		if (ret < 0) {
+			bridge->dev = NULL;
+			bridge->encoder = NULL;
+			return ret;
+		}
+	}
 
-	if (bridge->funcs->attach)
-		return bridge->funcs->attach(bridge);
+	if (previous)
+		previous->next = bridge;
+	else
+		encoder->bridge = bridge;
 
 	return 0;
 }