[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>
diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
index 69f65e2..74eed6b 100644
--- a/arch/powerpc/platforms/powermac/backlight.c
+++ b/arch/powerpc/platforms/powermac/backlight.c
@@ -15,6 +15,15 @@
#define OLD_BACKLIGHT_MAX 15
+static void pmac_backlight_key_worker(void *data);
+static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker, NULL);
+
+/* Although this variable is used in interrupt context, it makes no sense to
+ * protect it. No user is able to produce enough key events per second and
+ * notice the errors that might happen.
+ */
+static int pmac_backlight_key_queued;
+
/* Protect the pmac_backlight variable */
DEFINE_MUTEX(pmac_backlight_mutex);
@@ -71,7 +80,7 @@
return level;
}
-static void pmac_backlight_key(int direction)
+static void pmac_backlight_key_worker(void *data)
{
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight) {
@@ -82,7 +91,8 @@
props = pmac_backlight->props;
brightness = props->brightness +
- ((direction?-1:1) * (props->max_brightness / 15));
+ ((pmac_backlight_key_queued?-1:1) *
+ (props->max_brightness / 15));
if (brightness < 0)
brightness = 0;
@@ -97,14 +107,13 @@
mutex_unlock(&pmac_backlight_mutex);
}
-void pmac_backlight_key_up()
+void pmac_backlight_key(int direction)
{
- pmac_backlight_key(0);
-}
-
-void pmac_backlight_key_down()
-{
- pmac_backlight_key(1);
+ /* we can receive multiple interrupts here, but the scheduled work
+ * will run only once, with the last value
+ */
+ pmac_backlight_key_queued = direction;
+ schedule_work(&pmac_backlight_key_work);
}
int pmac_backlight_set_legacy_brightness(int brightness)
@@ -157,3 +166,7 @@
return result;
}
+
+EXPORT_SYMBOL_GPL(pmac_backlight);
+EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
+EXPORT_SYMBOL_GPL(pmac_has_backlight_type);