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backlight: Fix external uses of backlight internal semaphore

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backlight_device->sem has a very specific use as documented in the
header file. The external users of this are using it for a different
reason, to serialise access to the update_status() method.

backlight users were supposed to implement their own internal
serialisation of update_status() if needed but everyone is doing
things differently and incorrectly. Therefore add a global mutex to
take care of serialisation for everyone, once and for all.

Locking for get_brightness remains optional since most users don't
need it.

Also update the lcd class in a similar way.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
This commit is contained in:
Richard Purdie
2007-02-08 22:25:09 +00:00
parent a8db3c1948
commit 28ee086d5b
15 changed files with 76 additions and 76 deletions
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4
arch/powerpc/kernel/traps.c
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@@ -107,12 +107,10 @@ int die(const char *str, struct pt_regs *regs, long err)
if (machine_is(powermac) && pmac_backlight) {
struct backlight_properties *props;
down(&pmac_backlight->sem);
props = pmac_backlight->props;
props->brightness = props->max_brightness;
props->power = FB_BLANK_UNBLANK;
props->update_status(pmac_backlight);
up(&pmac_backlight->sem);
backlight_update_status(pmac_backlight);
}
mutex_unlock(&pmac_backlight_mutex);
#endif