[PATCH v2 5/6] drm/atomic: Add drm_atomic_helper_best_encoder()

["Noralf Trønnes" <noralf@tronnes.org>]

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>
---
 drivers/gpu/drm/drm_atomic_helper.c | 17 +++++++++++++++++
 include/drm/drm_atomic_helper.h     |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 46a3201..43a0b3d 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 0364287..ccca709 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);
-- 
2.8.2