backend/drm: add support for adaptive_sync_enabled

The vrr_capable and VRR_ENABLED properties are used.

backend/drm/drm.c

@@ -412,6 +412,43 @@ static bool drm_connector_commit_buffer(struct wlr_output *output) {
 	return true;
 }
 
+static void drm_connector_enable_adaptive_sync(struct wlr_output *output,
+		bool enabled) {
+	struct wlr_drm_connector *conn = get_drm_connector_from_output(output);
+	struct wlr_drm_backend *drm = get_drm_backend_from_backend(output->backend);
+
+	struct wlr_drm_crtc *crtc = conn->crtc;
+	if (!crtc) {
+		return;
+	}
+
+	uint64_t vrr_capable;
+	if (conn->props.vrr_capable == 0 ||
+			!get_drm_prop(drm->fd, conn->id, conn->props.vrr_capable,
+			&vrr_capable) || !vrr_capable) {
+		wlr_log(WLR_DEBUG, "Failed to enable adaptive sync: "
+			"connector '%s' doesn't support VRR", output->name);
+		return;
+	}
+
+	if (crtc->props.vrr_enabled == 0) {
+		wlr_log(WLR_DEBUG, "Failed to enable adaptive sync: "
+			"CRTC %"PRIu32" doesn't support VRR", crtc->id);
+		return;
+	}
+
+	if (drmModeObjectSetProperty(drm->fd, crtc->id, DRM_MODE_OBJECT_CRTC,
+			crtc->props.vrr_enabled, enabled) != 0) {
+		wlr_log_errno(WLR_ERROR, "drmModeObjectSetProperty(VRR_ENABLED) failed");
+		return;
+	}
+
+	output->adaptive_sync_status = enabled ? WLR_OUTPUT_ADAPTIVE_SYNC_ENABLED :
+		WLR_OUTPUT_ADAPTIVE_SYNC_DISABLED;
+	wlr_log(WLR_DEBUG, "VRR %s on connector '%s'",
+		enabled ? "enabled" : "disabled", output->name);
+}
+
 static bool drm_connector_set_custom_mode(struct wlr_output *output,
 	int32_t width, int32_t height, int32_t refresh);
 
@@ -446,6 +483,11 @@ static bool drm_connector_commit(struct wlr_output *output) {
 		}
 	}
 
+	if (output->pending.committed & WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED) {
+		drm_connector_enable_adaptive_sync(output,
+			output->pending.adaptive_sync_enabled);
+	}
+
 	// TODO: support modesetting with a buffer
 	if (output->pending.committed & WLR_OUTPUT_STATE_BUFFER &&
 			!(output->pending.committed & WLR_OUTPUT_STATE_MODE)) {

backend/drm/properties.c

@@ -24,6 +24,7 @@ static const struct prop_info connector_info[] = {
 	{ "EDID", INDEX(edid) },
 	{ "PATH", INDEX(path) },
 	{ "link-status", INDEX(link_status) },
+	{ "vrr_capable", INDEX(vrr_capable) },
 #undef INDEX
 };
 
@@ -33,6 +34,7 @@ static const struct prop_info crtc_info[] = {
 	{ "GAMMA_LUT", INDEX(gamma_lut) },
 	{ "GAMMA_LUT_SIZE", INDEX(gamma_lut_size) },
 	{ "MODE_ID", INDEX(mode_id) },
+	{ "VRR_ENABLED", INDEX(vrr_enabled) },
 	{ "rotation", INDEX(rotation) },
 	{ "scaling mode", INDEX(scaling_mode) },
 #undef INDEX

include/backend/drm/properties.h

@@ -16,6 +16,7 @@ union wlr_drm_connector_props {
 		uint32_t dpms;
 		uint32_t link_status; // not guaranteed to exist
 		uint32_t path;
+		uint32_t vrr_capable; // not guaranteed to exist
 
 		// atomic-modesetting only
 
@@ -29,6 +30,7 @@ union wlr_drm_crtc_props {
 		// Neither of these are guaranteed to exist
 		uint32_t rotation;
 		uint32_t scaling_mode;
+		uint32_t vrr_enabled;
 
 		// atomic-modesetting only