[PATCH] powermac: Combined fixes for backlight code

This patch fixes several problems:
- pmac_backlight_key() is called under interrupt context, and therefore
  can't use mutexes or semaphores, so defer the backlight level for
  later, as it's not critical (original code by Aristeu S. Rozanski F.
  <aris@valeta.org>).
- Add exports for functions that might be called from modules
- Fix Kconfig depdencies on PMAC_BACKLIGHT.
- Fix locking issues on calls from inside the driver (reported by
  Aristeu S. Rozanski F., too)
- Fix wrong calculation of backlight values in some of the drivers
- Replace pmac_backlight_key_up/down by inline functions

[akpm@osdl.org: fix function prototypes]
Signed-off-by: Michael Hanselmann <linux-kernel@hansmi.ch>
Acked-by: Aristeu S. Rozanski F. <aris@valeta.org>
Acked-by: Rene Nussbaumer <linux-kernel@killerfox.forkbomb.ch>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/asm-powerpc/backlight.h

@@ -16,13 +16,19 @@
 extern struct backlight_device *pmac_backlight;
 extern struct mutex pmac_backlight_mutex;
 
-extern void pmac_backlight_calc_curve(struct fb_info*);
 extern int pmac_backlight_curve_lookup(struct fb_info *info, int value);
 
 extern int pmac_has_backlight_type(const char *type);
 
-extern void pmac_backlight_key_up(void);
-extern void pmac_backlight_key_down(void);
+extern void pmac_backlight_key(int direction);
+static inline void pmac_backlight_key_up(void)
+{
+	pmac_backlight_key(0);
+}
+static inline void pmac_backlight_key_down(void)
+{
+	pmac_backlight_key(1);
+}
 
 extern int pmac_backlight_set_legacy_brightness(int brightness);
 extern int pmac_backlight_get_legacy_brightness(void);