drm/atomic: add connectors_changed to separate it from mode_changed, v2

This can be a separate case from mode_changed, when connectors stay the
same but only the mode is different. Drivers may choose to implement specific
optimizations to prevent a full modeset for this case.

Changes since v1:
- Update kerneldocs slightly.

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ander Conselvan de Oliveira <conselvan2@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

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
+ * update and adds any additional connectors needed for full modesets and calls
- * connectors needed for full modesets and calls down into ->mode_fixup
+ * down into ->mode_fixup functions of the driver backend.
- * 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);

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);
 }
 
 /**

include/drm/drm_atomic.h

@@ -166,7 +166,8 @@ int __must_check drm_atomic_async_commit(struct drm_atomic_state *state);
 static inline bool
 drm_atomic_crtc_needs_modeset(struct drm_crtc_state *state)
 {
-	return state->mode_changed || state->active_changed;
+	return state->mode_changed || state->active_changed ||
+	       state->connectors_changed;
 }
 
 

include/drm/drm_crtc.h

@@ -255,12 +255,13 @@ struct drm_atomic_state;
  * @crtc: backpointer to the CRTC
  * @enable: whether the CRTC should be enabled, gates all other state
  * @active: whether the CRTC is actively displaying (used for DPMS)
- * @mode_changed: for use by helpers and drivers when computing state updates
+ * @planes_changed: planes on this crtc are updated
- * @active_changed: for use by helpers and drivers when computing state updates
+ * @mode_changed: crtc_state->mode or crtc_state->enable has been changed
+ * @active_changed: crtc_state->active has been toggled.
+ * @connectors_changed: connectors to this crtc have been updated
  * @plane_mask: bitmask of (1 << drm_plane_index(plane)) of attached planes
  * @last_vblank_count: for helpers and drivers to capture the vblank of the
  * 	update to ensure framebuffer cleanup isn't done too early
- * @planes_changed: for use by helpers and drivers when computing state updates
  * @adjusted_mode: for use by helpers and drivers to compute adjusted mode timings
  * @mode: current mode timings
  * @event: optional pointer to a DRM event to signal upon completion of the
@@ -283,6 +284,7 @@ struct drm_crtc_state {
 	bool planes_changed : 1;
 	bool mode_changed : 1;
 	bool active_changed : 1;
+	bool connectors_changed : 1;
 
 	/* attached planes bitmask:
 	 * WARNING: transitional helpers do not maintain plane_mask so