Add atomic gamma setting

backend/drm/atomic.c

@@ -1,3 +1,4 @@
+#include <stdlib.h>
 #include <gbm.h>
 #include <xf86drm.h>
 #include <xf86drmMode.h>
@@ -195,9 +196,40 @@ static bool atomic_crtc_move_cursor(struct wlr_drm_backend *drm,
 	return atomic_end(drm->fd, &atom);
 }
 
+static bool atomic_crtc_set_gamma(struct wlr_drm_backend *drm,
+		struct wlr_drm_crtc *crtc, uint16_t *r, uint16_t *g, uint16_t *b,
+		uint32_t size) {
+	struct drm_color_lut *gamma = calloc(sizeof(struct drm_color_lut), size);
+
+	for (uint32_t i = 0; i < size; i++) {
+		gamma[i].red = r[i];
+		gamma[i].green = g[i];
+		gamma[i].blue = b[i];
+	}
+
+	if (crtc->gamma_lut != 0) {
+		drmModeDestroyPropertyBlob(drm->fd, crtc->gamma_lut);
+	}
+
+	if (drmModeCreatePropertyBlob(drm->fd, gamma,
+				sizeof(struct drm_color_lut) * size, &crtc->gamma_lut)) {
+		wlr_log_errno(L_ERROR, "Unable to create property blob");
+		return false;
+	}
+
+	free(gamma);
+
+	struct atomic atom;
+
+	atomic_begin(crtc, &atom);
+	atomic_add(&atom, crtc->id, crtc->props.gamma_lut, crtc->gamma_lut);
+	return atomic_end(drm->fd, &atom);
+}
+
 const struct wlr_drm_interface atomic_iface = {
 	.conn_enable = atomic_conn_enable,
 	.crtc_pageflip = atomic_crtc_pageflip,
 	.crtc_set_cursor = atomic_crtc_set_cursor,
 	.crtc_move_cursor = atomic_crtc_move_cursor,
+	.crtc_set_gamma = atomic_crtc_set_gamma,
 };

backend/drm/drm.c

@@ -169,6 +169,9 @@ void wlr_drm_resources_free(struct wlr_drm_backend *drm) {
 		if (crtc->mode_id) {
 			drmModeDestroyPropertyBlob(drm->fd, crtc->mode_id);
 		}
+		if (crtc->gamma_lut) {
+			drmModeDestroyPropertyBlob(drm->fd, crtc->gamma_lut);
+		}
 	}
 	for (size_t i = 0; i < drm->num_planes; ++i) {
 		struct wlr_drm_plane *plane = &drm->planes[i];
@@ -227,7 +230,7 @@ static void wlr_drm_connector_set_gamma(struct wlr_output *output,
 		uint32_t size, uint16_t *r, uint16_t *g, uint16_t *b) {
 	struct wlr_drm_connector *conn = (struct wlr_drm_connector *)output;
 	struct wlr_drm_backend *drm = (struct wlr_drm_backend *)output->backend;
-	drmModeCrtcSetGamma(drm->fd, conn->crtc->id, size, r, g, b);
+	drm->iface->crtc_set_gamma(drm, conn->crtc, r, g, b, size);
 }
 
 static uint32_t wlr_drm_connector_get_gamma_size(struct wlr_output *output) {

backend/drm/legacy.c

@@ -59,9 +59,17 @@ bool legacy_crtc_move_cursor(struct wlr_drm_backend *drm,
 	return !drmModeMoveCursor(drm->fd, crtc->id, x, y);
 }
 
+bool legacy_crtc_set_gamma(struct wlr_drm_backend *drm,
+		struct wlr_drm_crtc *crtc, uint16_t *r, uint16_t *g, uint16_t *b,
+		uint32_t size) {
+	return !drmModeCrtcSetGamma(drm->fd, crtc->id, size, r, g, b);
+}
+
+
 const struct wlr_drm_interface legacy_iface = {
 	.conn_enable = legacy_conn_enable,
 	.crtc_pageflip = legacy_crtc_pageflip,
 	.crtc_set_cursor = legacy_crtc_set_cursor,
 	.crtc_move_cursor = legacy_crtc_move_cursor,
+	.crtc_set_gamma = legacy_crtc_set_gamma,
 };

backend/drm/properties.c

@@ -28,6 +28,7 @@ static const struct prop_info connector_info[] = {
 static const struct prop_info crtc_info[] = {
 #define INDEX(name) (offsetof(union wlr_drm_crtc_props, name) / sizeof(uint32_t))
 	{ "ACTIVE",       INDEX(active) },
+	{ "GAMMA_LUT",    INDEX(gamma_lut) },
 	{ "MODE_ID",      INDEX(mode_id) },
 	{ "rotation",     INDEX(rotation) },
 	{ "scaling mode", INDEX(scaling_mode) },

include/backend/drm/drm.h

@@ -39,7 +39,10 @@ struct wlr_drm_plane {
 
 struct wlr_drm_crtc {
 	uint32_t id;
-	uint32_t mode_id; // atomic modesetting only
+
+	// Atomic modesetting only
+	uint32_t mode_id;
+	uint32_t gamma_lut;
 	drmModeAtomicReq *atomic;
 
 	union {

include/backend/drm/iface.h

@@ -27,6 +27,10 @@ struct wlr_drm_interface {
 	// Move the cursor on crtc
 	bool (*crtc_move_cursor)(struct wlr_drm_backend *drm,
 		struct wlr_drm_crtc *crtc, int x, int y);
+	// Set the gamma lut on crtc
+	bool (*crtc_set_gamma)(struct wlr_drm_backend *drm,
+			struct wlr_drm_crtc *crtc, uint16_t *r, uint16_t *g, uint16_t *b,
+			uint32_t size);
 };
 
 extern const struct wlr_drm_interface atomic_iface;

include/backend/drm/properties.h

@@ -32,8 +32,9 @@ union wlr_drm_crtc_props {
 
 		uint32_t active;
 		uint32_t mode_id;
+		uint32_t gamma_lut;
 	};
-	uint32_t props[4];
+	uint32_t props[5];
 };
 
 union wlr_drm_plane_props {