2 files changed, 34 insertions, 1 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 20be86d89a20..99365087645b 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -886,8 +886,12 @@ crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
                  * Each encoder has at most one connector (since we always steal
                  * it away), so we won't call mode_set hooks twice.
                  */
-                if (funcs && funcs->mode_set)
+                if (funcs && funcs->atomic_mode_set) {
+                        funcs->atomic_mode_set(encoder, new_crtc_state,
+                                               connector->state);
+                } else if (funcs && funcs->mode_set) {
                         funcs->mode_set(encoder, mode, adjusted_mode);
+                }
 
                 drm_bridge_mode_set(encoder->bridge, mode, adjusted_mode);
         }
diff --git a/include/drm/drm_modeset_helper_vtables.h b/include/drm/drm_modeset_helper_vtables.h
index b55f21857a98..686feec6b4c8 100644
--- a/include/drm/drm_modeset_helper_vtables.h
+++ b/include/drm/drm_modeset_helper_vtables.h
@@ -523,12 +523,41 @@ struct drm_encoder_helper_funcs {
          *
          * This callback is used both by the legacy CRTC helpers and the atomic
          * modeset helpers. It is optional in the atomic helpers.
+         *
+         * NOTE:
+         *
+         * If the driver uses the atomic modeset helpers and needs to inspect
+         * the connector state or connector display info during mode setting,
+         * @atomic_mode_set can be used instead.
          */
         void (*mode_set)(struct drm_encoder *encoder,
                          struct drm_display_mode *mode,
                          struct drm_display_mode *adjusted_mode);
 
         /**
+         * @atomic_mode_set:
+         *
+         * This callback is used to update the display mode of an encoder.
+         *
+         * Note that the display pipe is completely off when this function is
+         * called. Drivers which need hardware to be running before they program
+         * the new display mode (because they implement runtime PM) should not
+         * use this hook, because the helper library calls it only once and not
+         * every time the display pipeline is suspended using either DPMS or the
+         * new "ACTIVE" property. Such drivers should instead move all their
+         * encoder setup into the ->enable() callback.
+         *
+         * This callback is used by the atomic modeset helpers in place of the
+         * @mode_set callback, if set by the driver. It is optional and should
+         * be used instead of @mode_set if the driver needs to inspect the
+         * connector state or display info, since there is no direct way to
+         * go from the encoder to the current connector.
+         */
+        void (*atomic_mode_set)(struct drm_encoder *encoder,
+                                struct drm_crtc_state *crtc_state,
+                                struct drm_connector_state *conn_state);
+
+        /**
          * @get_crtc:
          *
          * This callback is used by the legacy CRTC helpers to work around