drm/atomic: Add drm_atomic_helper_best_encoder()

Add (struct drm_connector_helper_funcs *)->best_encoder callback helper
for connectors that support exactly 1 encoder, statically determined at
driver init time.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1462982962-10530-6-git-send-email-noralf@tronnes.org

2 files changed, 19 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 46a3201b9851..43a0b3dfa846 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2483,6 +2483,23 @@ backoff:
 EXPORT_SYMBOL(drm_atomic_helper_connector_dpms);
 
 /**
+ * drm_atomic_helper_best_encoder - Helper for &drm_connector_helper_funcs
+ *                                  ->best_encoder callback
+ * @connector: Connector control structure
+ *
+ * This is a &drm_connector_helper_funcs ->best_encoder callback helper for
+ * connectors that support exactly 1 encoder, statically determined at driver
+ * init time.
+ */
+struct drm_encoder *
+drm_atomic_helper_best_encoder(struct drm_connector *connector)
+{
+        WARN_ON(connector->encoder_ids[1]);
+        return drm_encoder_find(connector->dev, connector->encoder_ids[0]);
+}
+EXPORT_SYMBOL(drm_atomic_helper_best_encoder);
+
+/**
  * DOC: atomic state reset and initialization
  *
  * Both the drm core and the atomic helpers assume that there is always the full
diff --git a/include/drm/drm_atomic_helper.h b/include/drm/drm_atomic_helper.h
index 03642878bc51..ccca709a255b 100644
--- a/include/drm/drm_atomic_helper.h
+++ b/include/drm/drm_atomic_helper.h
@@ -110,6 +110,8 @@ int drm_atomic_helper_page_flip(struct drm_crtc *crtc,
                                 uint32_t flags);
 int drm_atomic_helper_connector_dpms(struct drm_connector *connector,
                                      int mode);
+struct drm_encoder *
+drm_atomic_helper_best_encoder(struct drm_connector *connector);
 
 /* default implementations for state handling */
 void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc);