2 files changed, 31 insertions, 10 deletions

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 99656815641d..10bcdd554501 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -124,7 +124,7 @@ steal_encoder(struct drm_atomic_state *state,
         if (IS_ERR(crtc_state))
                 return PTR_ERR(crtc_state);
 
-        crtc_state->mode_changed = true;
+        crtc_state->connectors_changed = true;
 
         list_for_each_entry(connector, &config->connector_list, head) {
                 if (connector->state->best_encoder != encoder)
@@ -174,14 +174,14 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx)
                         idx = drm_crtc_index(connector->state->crtc);
 
                         crtc_state = state->crtc_states[idx];
-                        crtc_state->mode_changed = true;
+                        crtc_state->connectors_changed = true;
                 }
 
                 if (connector_state->crtc) {
                         idx = drm_crtc_index(connector_state->crtc);
 
                         crtc_state = state->crtc_states[idx];
-                        crtc_state->mode_changed = true;
+                        crtc_state->connectors_changed = true;
                 }
         }
 
@@ -233,7 +233,7 @@ update_connector_routing(struct drm_atomic_state *state, int conn_idx)
         idx = drm_crtc_index(connector_state->crtc);
 
         crtc_state = state->crtc_states[idx];
-        crtc_state->mode_changed = true;
+        crtc_state->connectors_changed = true;
 
         DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d]\n",
                          connector->base.id,
@@ -256,7 +256,8 @@ mode_fixup(struct drm_atomic_state *state)
         bool ret;
 
         for_each_crtc_in_state(state, crtc, crtc_state, i) {
-                if (!crtc_state->mode_changed)
+                if (!crtc_state->mode_changed &&
+                    !crtc_state->connectors_changed)
                         continue;
 
                 drm_mode_copy(&crtc_state->adjusted_mode, &crtc_state->mode);
@@ -312,7 +313,8 @@ mode_fixup(struct drm_atomic_state *state)
         for_each_crtc_in_state(state, crtc, crtc_state, i) {
                 const struct drm_crtc_helper_funcs *funcs;
 
-                if (!crtc_state->mode_changed)
+                if (!crtc_state->mode_changed &&
+                    !crtc_state->connectors_changed)
                         continue;
 
                 funcs = crtc->helper_private;
@@ -338,9 +340,14 @@ mode_fixup(struct drm_atomic_state *state)
  *
  * Check the state object to see if the requested state is physically possible.
  * This does all the crtc and connector related computations for an atomic
- * update. It computes and updates crtc_state->mode_changed, adds any additional
- * connectors needed for full modesets and calls down into ->mode_fixup
- * functions of the driver backend.
+ * update and adds any additional connectors needed for full modesets and calls
+ * down into ->mode_fixup functions of the driver backend.
+ *
+ * crtc_state->mode_changed is set when the input mode is changed.
+ * crtc_state->connectors_changed is set when a connector is added or
+ * removed from the crtc.
+ * crtc_state->active_changed is set when crtc_state->active changes,
+ * which is used for dpms.
  *
  * IMPORTANT:
  *
@@ -373,7 +380,17 @@ drm_atomic_helper_check_modeset(struct drm_device *dev,
                 if (crtc->state->enable != crtc_state->enable) {
                         DRM_DEBUG_ATOMIC("[CRTC:%d] enable changed\n",
                                          crtc->base.id);
+
+                        /*
+                         * For clarity this assignment is done here, but
+                         * enable == 0 is only true when there are no
+                         * connectors and a NULL mode.
+                         *
+                         * The other way around is true as well. enable != 0
+                         * iff connectors are attached and a mode is set.
+                         */
                         crtc_state->mode_changed = true;
+                        crtc_state->connectors_changed = true;
                 }
         }
 
@@ -448,6 +465,9 @@ EXPORT_SYMBOL(drm_atomic_helper_check_modeset);
  * This does all the plane update related checks using by calling into the
  * ->atomic_check hooks provided by the driver.
  *
+ * It also sets crtc_state->planes_changed to indicate that a crtc has
+ * updated planes.
+ *
  * RETURNS
  * Zero for success or -errno
  */
@@ -2074,6 +2094,7 @@ void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
         state->mode_changed = false;
         state->active_changed = false;
         state->planes_changed = false;
+        state->connectors_changed = false;
         state->event = NULL;
 }
 EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index af0bcfee4771..07cee59edece 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -413,7 +413,7 @@ static const intel_limit_t intel_limits_bxt = {
 static bool
 needs_modeset(struct drm_crtc_state *state)
 {
-        return state->mode_changed || state->active_changed;
+        return drm_atomic_crtc_needs_modeset(state);
 }
 
 /**