compositor-drm: move backlight into drm_head

Backlight is driven per connector, hence it belongs in struct drm_head.

weston_output::set_backlight() API is remains per output so far. There
is no UI to control backlights per head and adding one would be
difficult for an output that has multiple cloned heads.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Acked-by: Derek Foreman <derekf@osg.samsung.com>

libweston/compositor-drm.c

@@ -407,6 +407,8 @@ struct drm_head {
 	struct drm_backend *backend;
 
 	struct drm_output *output; /* XXX: temporary */
+
+	struct backlight *backlight;
 };
 
 struct drm_output {
@@ -423,8 +425,6 @@ struct drm_output {
 	/* Holds the properties for the CRTC */
 	struct drm_property_info props_crtc[WDRM_CRTC__COUNT];
 
-	struct backlight *backlight;
-
 	int vblank_pending;
 	int page_flip_pending;
 	int atomic_complete_pending;
@@ -3808,12 +3808,12 @@ drm_subpixel_to_wayland(int drm_value)
 
 /* returns a value between 0-255 range, where higher is brighter */
 static uint32_t
-drm_get_backlight(struct drm_output *output)
+drm_get_backlight(struct drm_head *head)
 {
 	long brightness, max_brightness, norm;
 
-	brightness = backlight_get_brightness(output->backlight);
-	max_brightness = backlight_get_max_brightness(output->backlight);
+	brightness = backlight_get_brightness(head->backlight);
+	max_brightness = backlight_get_max_brightness(head->backlight);
 
 	/* convert it on a scale of 0 to 255 */
 	norm = (brightness * 255)/(max_brightness);
@@ -3825,21 +3825,21 @@ drm_get_backlight(struct drm_output *output)
 static void
 drm_set_backlight(struct weston_output *output_base, uint32_t value)
 {
-	struct drm_output *output = to_drm_output(output_base);
+	struct drm_head *head = to_drm_head(weston_output_get_first_head(output_base));
 	long max_brightness, new_brightness;
 
-	if (!output->backlight)
+	if (!head->backlight)
 		return;
 
 	if (value > 255)
 		return;
 
-	max_brightness = backlight_get_max_brightness(output->backlight);
+	max_brightness = backlight_get_max_brightness(head->backlight);
 
 	/* get denormalized value */
 	new_brightness = (value * max_brightness) / 255;
 
-	backlight_set_brightness(output->backlight, new_brightness);
+	backlight_set_brightness(head->backlight, new_brightness);
 }
 
 /**
@@ -4745,6 +4745,7 @@ drm_output_enable(struct weston_output *base)
 {
 	struct drm_output *output = to_drm_output(base);
 	struct drm_backend *b = to_drm_backend(base->compositor);
+	struct drm_head *head = to_drm_head(weston_output_get_first_head(base));
 	struct weston_mode *m;
 
 	if (b->pageflip_timeout)
@@ -4760,11 +4761,11 @@ drm_output_enable(struct weston_output *base)
 		goto err;
 	}
 
-	if (output->backlight) {
+	if (head->backlight) {
 		weston_log("Initialized backlight, device %s\n",
-			   output->backlight->path);
+			   head->backlight->path);
 		output->base.set_backlight = drm_set_backlight;
-		output->base.backlight_current = drm_get_backlight(output);
+		output->base.backlight_current = drm_get_backlight(head);
 	} else {
 		weston_log("Failed to initialize backlight\n");
 	}
@@ -4877,9 +4878,6 @@ drm_output_destroy(struct weston_output *base)
 	drm_property_info_free(output->props_conn, WDRM_CONNECTOR__COUNT);
 	drmModeFreeConnector(output->connector);
 
-	if (output->backlight)
-		backlight_destroy(output->backlight);
-
 	assert(!output->state_last);
 	drm_output_state_free(output->state_cur);
 
@@ -5005,6 +5003,8 @@ drm_head_create(struct drm_backend *backend, uint32_t connector_id,
 
 	head->backend = backend;
 
+	head->backlight = backlight_init(drm_device, connector->connector_type);
+
 	/* Unknown connection status is assumed disconnected. */
 	weston_head_set_connection_status(&head->base,
 				connector->connection == DRM_MODE_CONNECTED);
@@ -5031,6 +5031,10 @@ static void
 drm_head_destroy(struct drm_head *head)
 {
 	weston_head_release(&head->base);
+
+	if (head->backlight)
+		backlight_destroy(head->backlight);
+
 	free(head);
 }
 
@@ -5070,9 +5074,6 @@ create_output_for_connector(struct drm_backend *b,
 	output->connector = connector;
 	output->connector_id = connector->connector_id;
 
-	output->backlight = backlight_init(drm_device,
-					   connector->connector_type);
-
 	name = make_connector_name(connector);
 	weston_output_init(&output->base, b->compositor, name);
 	free(name);