fix(display): Don't require locking for backlight

Signed-off-by: Rahix <rahix@rahix.de>

epicardium/epicardium.h

@@ -1352,12 +1352,12 @@ API(API_DISP_FRAMEBUFFER, int epic_disp_framebuffer(union disp_framebuffer *fb))
 
 
 /**
- * Set the backlight brightness value
+ * Set the backlight brightness.
  *
- * :param brightness: brightness from 0 - 100
- * :return: ``0`` on success or negative value in case of an error:
+ * Note that this function does not require acquiring the display.
  *
- *    - ``-EBUSY``: Display was already locked from another task.
+ * :param brightness: brightness from 0 - 100
+ * :return: ``0`` on success or negative value in case of an error
  */
 API(API_DISP_BACKLIGHT, int epic_disp_backlight(uint16_t brightness));
 

epicardium/modules/display.c

@@ -173,11 +173,7 @@ int epic_disp_framebuffer(union disp_framebuffer *fb)
 
 int epic_disp_backlight(uint16_t brightness)
 {
-	int cl = check_lock();
-	if (cl < 0) {
-		return cl;
-	}
-
+	/* TODO: lock? */
 	LCD_SetBacklight(brightness);
 	return 0;
 }