backend/drm: remove wlr_drm_crtc.pending_modeset

Replace it with a new drm_connector_state_is_modeset function that
decides whether a modeset is necessary directly from the
wlr_output_state which is going to be applied.

backend/drm/atomic.c

@@ -169,8 +169,10 @@ static bool atomic_crtc_commit(struct wlr_drm_backend *drm,
 	struct wlr_output *output = &conn->output;
 	struct wlr_drm_crtc *crtc = conn->crtc;
 
+	bool modeset = drm_connector_state_is_modeset(state);
+
 	uint32_t mode_id = crtc->mode_id;
-	if (crtc->pending_modeset) {
+	if (modeset) {
 		if (!create_mode_blob(drm, crtc, &mode_id)) {
 			return false;
 		}
@@ -203,7 +205,7 @@ static bool atomic_crtc_commit(struct wlr_drm_backend *drm,
 		vrr_enabled = state->adaptive_sync_enabled;
 	}
 
-	if (crtc->pending_modeset) {
+	if (modeset) {
 		flags |= DRM_MODE_ATOMIC_ALLOW_MODESET;
 	} else if (!(flags & DRM_MODE_ATOMIC_TEST_ONLY)) {
 		flags |= DRM_MODE_ATOMIC_NONBLOCK;
@@ -213,7 +215,7 @@ static bool atomic_crtc_commit(struct wlr_drm_backend *drm,
 	atomic_begin(&atom);
 	atomic_add(&atom, conn->id, conn->props.crtc_id,
 		crtc->pending.active ? crtc->id : 0);
-	if (crtc->pending_modeset && crtc->pending.active &&
+	if (modeset && crtc->pending.active &&
 			conn->props.link_status != 0) {
 		atomic_add(&atom, conn->id, conn->props.link_status,
 			DRM_MODE_LINK_STATUS_GOOD);

backend/drm/drm.c

@@ -345,7 +345,6 @@ static bool drm_crtc_commit(struct wlr_drm_connector *conn,
 			drm_fb_clear(&crtc->cursor->pending_fb);
 		}
 	}
-	crtc->pending_modeset = false;
 	return ok;
 }
 
@@ -358,7 +357,7 @@ static bool drm_crtc_page_flip(struct wlr_drm_connector *conn,
 	// page-flip, either a blocking modeset. When performing a blocking modeset
 	// we'll wait for all queued page-flips to complete, so we don't need this
 	// safeguard.
-	if (conn->pending_page_flip_crtc && !crtc->pending_modeset) {
+	if (conn->pending_page_flip_crtc && !drm_connector_state_is_modeset(state)) {
 		wlr_drm_conn_log(conn, WLR_ERROR, "Failed to page-flip output: "
 			"a page-flip is already pending");
 		return false;
@@ -681,7 +680,6 @@ static bool drm_connector_init_renderer(struct wlr_drm_connector *conn,
 	}
 	struct wlr_drm_plane *plane = crtc->primary;
 
-	crtc->pending_modeset = true;
 	crtc->pending.active = true;
 	crtc->pending.mode = mode;
 
@@ -705,7 +703,6 @@ static bool drm_connector_init_renderer(struct wlr_drm_connector *conn,
 			"retrying without modifiers");
 		modifiers = false;
 
-		crtc->pending_modeset = true;
 		crtc->pending.active = true;
 		crtc->pending.mode = mode;
 
@@ -755,7 +752,6 @@ bool drm_connector_set_mode(struct wlr_drm_connector *conn,
 
 	if (wlr_mode == NULL) {
 		if (conn->crtc != NULL) {
-			conn->crtc->pending_modeset = true;
 			conn->crtc->pending.active = false;
 			if (!drm_crtc_commit(conn, state, 0)) {
 				return false;
@@ -1041,6 +1037,11 @@ uint32_t wlr_drm_connector_get_id(struct wlr_output *output) {
 	return conn->id;
 }
 
+bool drm_connector_state_is_modeset(const struct wlr_output_state *state) {
+	return state->committed &
+		(WLR_OUTPUT_STATE_ENABLED | WLR_OUTPUT_STATE_MODE);
+}
+
 static const int32_t subpixel_map[] = {
 	[DRM_MODE_SUBPIXEL_UNKNOWN] = WL_OUTPUT_SUBPIXEL_UNKNOWN,
 	[DRM_MODE_SUBPIXEL_HORIZONTAL_RGB] = WL_OUTPUT_SUBPIXEL_HORIZONTAL_RGB,
@@ -1059,7 +1060,6 @@ static void dealloc_crtc(struct wlr_drm_connector *conn) {
 	wlr_drm_conn_log(conn, WLR_DEBUG, "De-allocating CRTC %zu",
 		conn->crtc - drm->crtcs);
 
-	conn->crtc->pending_modeset = true;
 	conn->crtc->pending.active = false;
 	struct wlr_output_state state = {
 		.committed = WLR_OUTPUT_STATE_ENABLED,

backend/drm/legacy.c

@@ -26,7 +26,7 @@ static bool legacy_crtc_commit(struct wlr_drm_backend *drm,
 		fb_id = fb->id;
 	}
 
-	if (crtc->pending_modeset) {
+	if (drm_connector_state_is_modeset(state)) {
 		uint32_t *conns = NULL;
 		size_t conns_len = 0;
 		drmModeModeInfo *mode = NULL;

include/backend/drm/drm.h

@@ -49,7 +49,6 @@ struct wlr_drm_crtc_state {
 struct wlr_drm_crtc {
 	uint32_t id;
 
-	bool pending_modeset;
 	struct wlr_drm_crtc_state pending, current;
 
 	// Atomic modesetting only
@@ -160,6 +159,8 @@ size_t drm_crtc_get_gamma_lut_size(struct wlr_drm_backend *drm,
 
 struct wlr_drm_fb *plane_get_next_fb(struct wlr_drm_plane *plane);
 
+bool drm_connector_state_is_modeset(const struct wlr_output_state *state);
+
 #define wlr_drm_conn_log(conn, verb, fmt, ...) \
 	wlr_log(verb, "connector %s: " fmt, conn->name, ##__VA_ARGS__)
 #define wlr_drm_conn_log_errno(conn, verb, fmt, ...) \