Remove get_presentation_clock from wlr_backend interface

backend/backend.c

@@ -153,13 +153,6 @@ static struct wlr_session *session_create_and_wait(struct wl_display *disp) {
 	return session;
 }
 
-clockid_t wlr_backend_get_presentation_clock(struct wlr_backend *backend) {
-	if (backend->impl->get_presentation_clock) {
-		return backend->impl->get_presentation_clock(backend);
-	}
-	return CLOCK_MONOTONIC;
-}
-
 int wlr_backend_get_drm_fd(struct wlr_backend *backend) {
 	if (!backend->impl->get_drm_fd) {
 		return -1;

backend/drm/backend.c

@@ -66,11 +66,6 @@ static void backend_destroy(struct wlr_backend *backend) {
 	free(drm);
 }
 
-static clockid_t backend_get_presentation_clock(struct wlr_backend *backend) {
-	struct wlr_drm_backend *drm = get_drm_backend_from_backend(backend);
-	return drm->clock;
-}
-
 static int backend_get_drm_fd(struct wlr_backend *backend) {
 	struct wlr_drm_backend *drm = get_drm_backend_from_backend(backend);
 
@@ -88,7 +83,6 @@ static uint32_t drm_backend_get_buffer_caps(struct wlr_backend *backend) {
 static const struct wlr_backend_impl backend_impl = {
 	.start = backend_start,
 	.destroy = backend_destroy,
-	.get_presentation_clock = backend_get_presentation_clock,
 	.get_drm_fd = backend_get_drm_fd,
 	.get_buffer_caps = drm_backend_get_buffer_caps,
 };

backend/drm/drm.c

@@ -72,6 +72,11 @@ bool check_drm_features(struct wlr_drm_backend *drm) {
 		return false;
 	}
 
+	if (drmGetCap(drm->fd, DRM_CAP_TIMESTAMP_MONOTONIC, &cap) || !cap) {
+		wlr_log(WLR_ERROR, "DRM_CAP_TIMESTAMP_MONOTONIC unsupported");
+		return false;
+	}
+
 	const char *no_atomic = getenv("WLR_DRM_NO_ATOMIC");
 	if (no_atomic && strcmp(no_atomic, "1") == 0) {
 		wlr_log(WLR_DEBUG,
@@ -86,14 +91,11 @@ bool check_drm_features(struct wlr_drm_backend *drm) {
 		drm->iface = &atomic_iface;
 	}
 
-	int ret = drmGetCap(drm->fd, DRM_CAP_TIMESTAMP_MONOTONIC, &cap);
-	drm->clock = (ret == 0 && cap == 1) ? CLOCK_MONOTONIC : CLOCK_REALTIME;
-
 	const char *no_modifiers = getenv("WLR_DRM_NO_MODIFIERS");
 	if (no_modifiers != NULL && strcmp(no_modifiers, "1") == 0) {
 		wlr_log(WLR_DEBUG, "WLR_DRM_NO_MODIFIERS set, disabling modifiers");
 	} else {
-		ret = drmGetCap(drm->fd, DRM_CAP_ADDFB2_MODIFIERS, &cap);
+		int ret = drmGetCap(drm->fd, DRM_CAP_ADDFB2_MODIFIERS, &cap);
 		drm->addfb2_modifiers = ret == 0 && cap == 1;
 		wlr_log(WLR_DEBUG, "ADDFB2 modifiers %s",
 			drm->addfb2_modifiers ? "supported" : "unsupported");

backend/multi/backend.c

@@ -82,20 +82,6 @@ static struct wlr_session *multi_backend_get_session(
 	return backend->session;
 }
 
-static clockid_t multi_backend_get_presentation_clock(
-		struct wlr_backend *backend) {
-	struct wlr_multi_backend *multi = multi_backend_from_backend(backend);
-
-	struct subbackend_state *sub;
-	wl_list_for_each(sub, &multi->backends, link) {
-		if (sub->backend->impl->get_presentation_clock) {
-			return wlr_backend_get_presentation_clock(sub->backend);
-		}
-	}
-
-	return CLOCK_MONOTONIC;
-}
-
 static int multi_backend_get_drm_fd(struct wlr_backend *backend) {
 	struct wlr_multi_backend *multi = multi_backend_from_backend(backend);
 
@@ -114,7 +100,6 @@ static const struct wlr_backend_impl backend_impl = {
 	.destroy = multi_backend_destroy,
 	.get_renderer = multi_backend_get_renderer,
 	.get_session = multi_backend_get_session,
-	.get_presentation_clock = multi_backend_get_presentation_clock,
 	.get_drm_fd = multi_backend_get_drm_fd,
 };
 

include/backend/drm/drm.h

@@ -57,7 +57,6 @@ struct wlr_drm_backend {
 
 	struct wlr_drm_backend *parent;
 	const struct wlr_drm_interface *iface;
-	clockid_t clock;
 	bool addfb2_modifiers;
 
 	int fd;

include/wlr/backend/interface.h

@@ -18,7 +18,6 @@ struct wlr_backend_impl {
 	void (*destroy)(struct wlr_backend *backend);
 	struct wlr_renderer *(*get_renderer)(struct wlr_backend *backend);
 	struct wlr_session *(*get_session)(struct wlr_backend *backend);
-	clockid_t (*get_presentation_clock)(struct wlr_backend *backend);
 	int (*get_drm_fd)(struct wlr_backend *backend);
 	uint32_t (*get_buffer_caps)(struct wlr_backend *backend);
 };

include/wlr/types/wlr_presentation_time.h

@@ -20,7 +20,6 @@ struct wlr_output_event_present;
 struct wlr_presentation {
 	struct wl_global *global;
 	struct wl_list feedbacks; // wlr_presentation_feedback::link
-	clockid_t clock;
 
 	struct {
 		struct wl_signal destroy;

types/wlr_output.c

@@ -961,9 +961,8 @@ void wlr_output_send_present(struct wlr_output *output,
 
 	if (event->presented && event->when == NULL) {
 		struct timespec now;
-		clockid_t clock = wlr_backend_get_presentation_clock(output->backend);
 		errno = 0;
-		if (clock_gettime(clock, &now) != 0) {
+		if (clock_gettime(CLOCK_MONOTONIC, &now) != 0) {
 			wlr_log_errno(WLR_ERROR, "failed to send output present event: "
 				"failed to read clock");
 			return;

types/wlr_presentation_time.c

@@ -1,7 +1,8 @@
-#define _POSIX_C_SOURCE 199309L
+#define _POSIX_C_SOURCE 200809L
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
+#include <time.h>
 #include <wlr/types/wlr_presentation_time.h>
 #include <wlr/types/wlr_surface.h>
 #include <wlr/backend.h>
@@ -159,7 +160,7 @@ static void presentation_bind(struct wl_client *client, void *data,
 	wl_resource_set_implementation(resource, &presentation_impl, presentation,
 		NULL);
 
-	wp_presentation_send_clock_id(resource, (uint32_t)presentation->clock);
+	wp_presentation_send_clock_id(resource, CLOCK_MONOTONIC);
 }
 
 static void handle_display_destroy(struct wl_listener *listener, void *data) {
@@ -186,8 +187,6 @@ struct wlr_presentation *wlr_presentation_create(struct wl_display *display,
 		return NULL;
 	}
 
-	presentation->clock = wlr_backend_get_presentation_clock(backend);
-
 	wl_list_init(&presentation->feedbacks);
 	wl_signal_init(&presentation->events.destroy);