Revert r18947, and add a comment why the backlight functions are wanted on all targets.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@18949 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 7 insertions, 2 deletions

diff --git a/apps/plugin.c b/apps/plugin.c
index 9a7e9b578c..13c829805f 100644
--- a/apps/plugin.c
+++ b/apps/plugin.c
@@ -147,7 +147,6 @@ static const struct plugin_api rockbox_api = {
     gui_scrollbar_draw,
 #endif
 
-#ifdef HAVE_BACKLIGHT
     backlight_on,
     backlight_off,
     backlight_set_timeout,
@@ -159,7 +158,6 @@ static const struct plugin_api rockbox_api = {
     backlight_set_timeout_plugged,
 #endif
     is_backlight_on,
-#endif /* HAVE_BACKLIGHT */
     splash,
     splashf,
 
diff --git a/apps/plugin.h b/apps/plugin.h
index 634bbed0d8..4f747ea2b1 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -246,6 +246,13 @@ struct plugin_api {
 #endif  /* HAVE_LCD_BITMAP */
 
     /* backlight */
+    /* The backlight_* functions must be present in the API regardless whether
+     * HAVE_BACKLIGHT is defined or not. The reason is that the stock Ondio has
+     * no backlight but can be modded to have backlight (it's prepared on the
+     * PCB). This makes backlight an all-target feature API wise, and keeps API
+     * compatible between stock and modded Ondio.
+     * For OLED targets like the Sansa Clip, the backlight_* functions control
+     * the display enable, which has essentially the same effect. */
     void (*backlight_on)(void);
     void (*backlight_off)(void);
     void (*backlight_set_timeout)(int index);