1 files changed, 15 insertions, 0 deletions
diff --git a/backend/drm/legacy.c b/backend/drm/legacy.c
index ca23bb1c..7c18b3e3 100644
--- a/backend/drm/legacy.c
+++ b/backend/drm/legacy.c
@@ -8,9 +8,24 @@
 #include "backend/drm/iface.h"
 #include "backend/drm/util.h"
 
+static bool legacy_crtc_test(struct wlr_drm_connector *conn,
+		const struct wlr_output_state *state) {
+	if ((state->committed & WLR_OUTPUT_STATE_BUFFER) &&
+			state->buffer_type == WLR_OUTPUT_STATE_BUFFER_SCANOUT) {
+		wlr_drm_conn_log(conn, WLR_DEBUG,
+			"Cannot use direct scan-out with legacy KMS API");
+		return false;
+	}
+
+	return true;
+}
+
 static bool legacy_crtc_commit(struct wlr_drm_backend *drm,
 		struct wlr_drm_connector *conn, const struct wlr_output_state *state,
 		uint32_t flags, bool test_only) {
+	if (!legacy_crtc_test(conn, state)) {
+		return false;
+	}
 	if (test_only) {
 		return true;
 	}