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author | Richard Purdie <rpurdie@rpsys.net> | 2007-02-08 22:25:09 +0000 |
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committer | Richard Purdie <rpurdie@rpsys.net> | 2007-02-20 08:38:45 +0000 |
commit | 28ee086d5b36aab2931f6740e409bb0fb6c65e5f (patch) | |
tree | 0a308c80affcc39c2c869f29f1109e5ee9d6140f /arch/powerpc | |
parent | a8db3c1948eb30cd6988b5b96b654f591e6280b1 (diff) | |
download | linux-3.10-28ee086d5b36aab2931f6740e409bb0fb6c65e5f.tar.gz linux-3.10-28ee086d5b36aab2931f6740e409bb0fb6c65e5f.tar.bz2 linux-3.10-28ee086d5b36aab2931f6740e409bb0fb6c65e5f.zip |
backlight: Fix external uses of backlight internal semaphore
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>
Diffstat (limited to 'arch/powerpc')
-rw-r--r-- | arch/powerpc/kernel/traps.c | 4 | ||||
-rw-r--r-- | arch/powerpc/platforms/powermac/backlight.c | 19 |
2 files changed, 6 insertions, 17 deletions
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index dcc6f159fd9..35ce07b6a5b 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -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 diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c index c3a89414ddc..1be358c1448 100644 --- a/arch/powerpc/platforms/powermac/backlight.c +++ b/arch/powerpc/platforms/powermac/backlight.c @@ -37,7 +37,9 @@ static int pmac_backlight_set_legacy_queued; */ static atomic_t kernel_backlight_disabled = ATOMIC_INIT(0); -/* Protect the pmac_backlight variable */ +/* Protect the pmac_backlight variable below. + You should hold this lock when using the pmac_backlight pointer to + prevent its potential removal. */ DEFINE_MUTEX(pmac_backlight_mutex); /* Main backlight storage @@ -49,9 +51,6 @@ DEFINE_MUTEX(pmac_backlight_mutex); * internal display, it doesn't matter. Other backlight drivers can be used * independently. * - * Lock ordering: - * pmac_backlight_mutex (global, main backlight) - * pmac_backlight->sem (backlight class) */ struct backlight_device *pmac_backlight; @@ -104,7 +103,6 @@ static void pmac_backlight_key_worker(struct work_struct *work) struct backlight_properties *props; int brightness; - down(&pmac_backlight->sem); props = pmac_backlight->props; brightness = props->brightness + @@ -117,9 +115,7 @@ static void pmac_backlight_key_worker(struct work_struct *work) brightness = props->max_brightness; props->brightness = brightness; - props->update_status(pmac_backlight); - - up(&pmac_backlight->sem); + backlight_update_status(pmac_backlight); } mutex_unlock(&pmac_backlight_mutex); } @@ -145,7 +141,6 @@ static int __pmac_backlight_set_legacy_brightness(int brightness) if (pmac_backlight) { struct backlight_properties *props; - down(&pmac_backlight->sem); props = pmac_backlight->props; props->brightness = brightness * (props->max_brightness + 1) / @@ -156,8 +151,7 @@ static int __pmac_backlight_set_legacy_brightness(int brightness) else if (props->brightness < 0) props->brightness = 0; - props->update_status(pmac_backlight); - up(&pmac_backlight->sem); + backlight_update_status(pmac_backlight); error = 0; } @@ -196,14 +190,11 @@ int pmac_backlight_get_legacy_brightness() if (pmac_backlight) { struct backlight_properties *props; - down(&pmac_backlight->sem); props = pmac_backlight->props; result = props->brightness * (OLD_BACKLIGHT_MAX + 1) / (props->max_brightness + 1); - - up(&pmac_backlight->sem); } mutex_unlock(&pmac_backlight_mutex); |