From 28ee086d5b36aab2931f6740e409bb0fb6c65e5f Mon Sep 17 00:00:00 2001 From: Richard Purdie Date: Thu, 8 Feb 2007 22:25:09 +0000 Subject: [PATCH] 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 --- arch/powerpc/kernel/traps.c | 4 +--- arch/powerpc/platforms/powermac/backlight.c | 19 +++++-------------- drivers/macintosh/via-pmu-backlight.c | 4 +--- drivers/misc/asus-laptop.c | 20 +++++--------------- drivers/usb/misc/appledisplay.c | 6 ------ drivers/video/aty/aty128fb.c | 6 +----- drivers/video/aty/atyfb_base.c | 6 +----- drivers/video/aty/radeon_backlight.c | 4 +--- drivers/video/backlight/backlight.c | 10 ++++------ drivers/video/backlight/lcd.c | 1 + drivers/video/chipsfb.c | 8 ++------ drivers/video/nvidia/nv_backlight.c | 6 +----- drivers/video/riva/fbdev.c | 6 +----- include/linux/backlight.h | 26 ++++++++++++++++++++++++++ include/linux/lcd.h | 26 ++++++++++++++++++++++++++ 15 files changed, 76 insertions(+), 76 deletions(-) diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index dcc6f15..35ce07b 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 c3a8941..1be358c 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); diff --git a/drivers/macintosh/via-pmu-backlight.c b/drivers/macintosh/via-pmu-backlight.c index db8bcc3..7ba2042 100644 --- a/drivers/macintosh/via-pmu-backlight.c +++ b/drivers/macintosh/via-pmu-backlight.c @@ -166,11 +166,9 @@ void __init pmu_backlight_init() pmu_backlight_data.max_brightness / 15); } - down(&bd->sem); bd->props->brightness = level; bd->props->power = FB_BLANK_UNBLANK; - bd->props->update_status(bd); - up(&bd->sem); + backlight_update_status(bd); mutex_lock(&pmac_backlight_mutex); if (!pmac_backlight) diff --git a/drivers/misc/asus-laptop.c b/drivers/misc/asus-laptop.c index d15ee5e..7ace5b9 100644 --- a/drivers/misc/asus-laptop.c +++ b/drivers/misc/asus-laptop.c @@ -348,13 +348,8 @@ static void lcd_blank(int blank) struct backlight_device *bd = asus_backlight_device; if (bd) { - down(&bd->sem); - if (likely(bd->props)) { - bd->props->power = blank; - if (likely(bd->props->update_status)) - bd->props->update_status(bd); - } - up(&bd->sem); + bd->props->power = blank; + backlight_update_status(bd); } } @@ -1028,14 +1023,9 @@ static int asus_backlight_init(struct device *dev) asus_backlight_device = bd; - down(&bd->sem); - if (likely(bd->props)) { - bd->props->brightness = read_brightness(NULL); - bd->props->power = FB_BLANK_UNBLANK; - if (likely(bd->props->update_status)) - bd->props->update_status(bd); - } - up(&bd->sem); + bd->props->brightness = read_brightness(NULL); + bd->props->power = FB_BLANK_UNBLANK; + backlight_update_status(bd); } return 0; } diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c index 416cde5..cd2c557 100644 --- a/drivers/usb/misc/appledisplay.c +++ b/drivers/usb/misc/appledisplay.c @@ -189,11 +189,9 @@ static void appledisplay_work(struct work_struct *work) container_of(work, struct appledisplay, work.work); int retval; - up(&pdata->bd->sem); retval = appledisplay_bl_get_brightness(pdata->bd); if (retval >= 0) pdata->bd->props->brightness = retval; - down(&pdata->bd->sem); /* Poll again in about 125ms if there's still a button pressed */ if (pdata->button_pressed) @@ -288,9 +286,7 @@ static int appledisplay_probe(struct usb_interface *iface, } /* Try to get brightness */ - up(&pdata->bd->sem); brightness = appledisplay_bl_get_brightness(pdata->bd); - down(&pdata->bd->sem); if (brightness < 0) { retval = brightness; @@ -299,9 +295,7 @@ static int appledisplay_probe(struct usb_interface *iface, } /* Set brightness in backlight device */ - up(&pdata->bd->sem); pdata->bd->props->brightness = brightness; - down(&pdata->bd->sem); /* save our data pointer in the interface device */ usb_set_intfdata(iface, pdata); diff --git a/drivers/video/aty/aty128fb.c b/drivers/video/aty/aty128fb.c index 1fa211c..5d8f73b 100644 --- a/drivers/video/aty/aty128fb.c +++ b/drivers/video/aty/aty128fb.c @@ -1807,10 +1807,8 @@ static void aty128_bl_set_power(struct fb_info *info, int power) mutex_lock(&info->bl_mutex); if (info->bl_dev) { - down(&info->bl_dev->sem); info->bl_dev->props->power = power; __aty128_bl_update_status(info->bl_dev); - up(&info->bl_dev->sem); } mutex_unlock(&info->bl_mutex); @@ -1847,11 +1845,9 @@ static void aty128_bl_init(struct aty128fb_par *par) 219 * FB_BACKLIGHT_MAX / MAX_LEVEL); mutex_unlock(&info->bl_mutex); - down(&bd->sem); bd->props->brightness = aty128_bl_data.max_brightness; bd->props->power = FB_BLANK_UNBLANK; - bd->props->update_status(bd); - up(&bd->sem); + backlight_update_status(bd); #ifdef CONFIG_PMAC_BACKLIGHT mutex_lock(&pmac_backlight_mutex); diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c index 5ea5a00..23deb35 100644 --- a/drivers/video/aty/atyfb_base.c +++ b/drivers/video/aty/atyfb_base.c @@ -2188,10 +2188,8 @@ static void aty_bl_set_power(struct fb_info *info, int power) mutex_lock(&info->bl_mutex); if (info->bl_dev) { - down(&info->bl_dev->sem); info->bl_dev->props->power = power; __aty_bl_update_status(info->bl_dev); - up(&info->bl_dev->sem); } mutex_unlock(&info->bl_mutex); @@ -2224,11 +2222,9 @@ static void aty_bl_init(struct atyfb_par *par) 0xFF * FB_BACKLIGHT_MAX / MAX_LEVEL); mutex_unlock(&info->bl_mutex); - down(&bd->sem); bd->props->brightness = aty_bl_data.max_brightness; bd->props->power = FB_BLANK_UNBLANK; - bd->props->update_status(bd); - up(&bd->sem); + backlight_update_status(bd); #ifdef CONFIG_PMAC_BACKLIGHT mutex_lock(&pmac_backlight_mutex); diff --git a/drivers/video/aty/radeon_backlight.c b/drivers/video/aty/radeon_backlight.c index 8b66df6..9cfceca 100644 --- a/drivers/video/aty/radeon_backlight.c +++ b/drivers/video/aty/radeon_backlight.c @@ -194,11 +194,9 @@ void radeonfb_bl_init(struct radeonfb_info *rinfo) 217 * FB_BACKLIGHT_MAX / MAX_RADEON_LEVEL); mutex_unlock(&rinfo->info->bl_mutex); - down(&bd->sem); bd->props->brightness = radeon_bl_data.max_brightness; bd->props->power = FB_BLANK_UNBLANK; - bd->props->update_status(bd); - up(&bd->sem); + backlight_update_status(bd); #ifdef CONFIG_PMAC_BACKLIGHT mutex_lock(&pmac_backlight_mutex); diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 7a85be4..347081d 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -37,8 +37,7 @@ static int fb_notifier_callback(struct notifier_block *self, if (!bd->props->check_fb || bd->props->check_fb(evdata->info)) { bd->props->fb_blank = *(int *)evdata->data; - if (bd->props && bd->props->update_status) - bd->props->update_status(bd); + backlight_update_status(bd); } up(&bd->sem); return 0; @@ -97,8 +96,7 @@ static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, if (bd->props) { pr_debug("backlight: set power to %d\n", power); bd->props->power = power; - if (bd->props->update_status) - bd->props->update_status(bd); + backlight_update_status(bd); rc = count; } up(&bd->sem); @@ -140,8 +138,7 @@ static ssize_t backlight_store_brightness(struct class_device *cdev, const char pr_debug("backlight: set brightness to %d\n", brightness); bd->props->brightness = brightness; - if (bd->props->update_status) - bd->props->update_status(bd); + backlight_update_status(bd); rc = count; } } @@ -230,6 +227,7 @@ struct backlight_device *backlight_device_register(const char *name, if (!new_bd) return ERR_PTR(-ENOMEM); + mutex_init(&new_bd->update_lock); init_MUTEX(&new_bd->sem); new_bd->props = bp; memset(&new_bd->class_dev, 0, sizeof(new_bd->class_dev)); diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c index 9590248..1e1e61a 100644 --- a/drivers/video/backlight/lcd.c +++ b/drivers/video/backlight/lcd.c @@ -198,6 +198,7 @@ struct lcd_device *lcd_device_register(const char *name, void *devdata, return ERR_PTR(-ENOMEM); init_MUTEX(&new_ld->sem); + mutex_init(&new_ld->update_lock); new_ld->props = lp; memset(&new_ld->class_dev, 0, sizeof(new_ld->class_dev)); new_ld->class_dev.class = &lcd_class; diff --git a/drivers/video/chipsfb.c b/drivers/video/chipsfb.c index 73cb426..9a656bc 100644 --- a/drivers/video/chipsfb.c +++ b/drivers/video/chipsfb.c @@ -153,13 +153,11 @@ static int chipsfb_blank(int blank, struct fb_info *info) * useful at blank = 1 too (saves battery, extends backlight * life) */ - down(&pmac_backlight->sem); if (blank) pmac_backlight->props->power = FB_BLANK_POWERDOWN; else pmac_backlight->props->power = FB_BLANK_UNBLANK; - pmac_backlight->props->update_status(pmac_backlight); - up(&pmac_backlight->sem); + backlight_update_status(pmac_backlight); } mutex_unlock(&pmac_backlight_mutex); @@ -415,10 +413,8 @@ chipsfb_pci_init(struct pci_dev *dp, const struct pci_device_id *ent) /* turn on the backlight */ mutex_lock(&pmac_backlight_mutex); if (pmac_backlight) { - down(&pmac_backlight->sem); pmac_backlight->props->power = FB_BLANK_UNBLANK; - pmac_backlight->props->update_status(pmac_backlight); - up(&pmac_backlight->sem); + backlight_update_status(pmac_backlight); } mutex_unlock(&pmac_backlight_mutex); #endif /* CONFIG_PMAC_BACKLIGHT */ diff --git a/drivers/video/nvidia/nv_backlight.c b/drivers/video/nvidia/nv_backlight.c index 4254c09..f5e42d0 100644 --- a/drivers/video/nvidia/nv_backlight.c +++ b/drivers/video/nvidia/nv_backlight.c @@ -114,10 +114,8 @@ void nvidia_bl_set_power(struct fb_info *info, int power) mutex_lock(&info->bl_mutex); if (info->bl_dev) { - down(&info->bl_dev->sem); info->bl_dev->props->power = power; __nvidia_bl_update_status(info->bl_dev); - up(&info->bl_dev->sem); } mutex_unlock(&info->bl_mutex); @@ -154,11 +152,9 @@ void nvidia_bl_init(struct nvidia_par *par) 0x534 * FB_BACKLIGHT_MAX / MAX_LEVEL); mutex_unlock(&info->bl_mutex); - down(&bd->sem); bd->props->brightness = nvidia_bl_data.max_brightness; bd->props->power = FB_BLANK_UNBLANK; - bd->props->update_status(bd); - up(&bd->sem); + backlight_update_status(bd); #ifdef CONFIG_PMAC_BACKLIGHT mutex_lock(&pmac_backlight_mutex); diff --git a/drivers/video/riva/fbdev.c b/drivers/video/riva/fbdev.c index fd82571..b70d18f 100644 --- a/drivers/video/riva/fbdev.c +++ b/drivers/video/riva/fbdev.c @@ -357,10 +357,8 @@ static void riva_bl_set_power(struct fb_info *info, int power) mutex_lock(&info->bl_mutex); if (info->bl_dev) { - down(&info->bl_dev->sem); info->bl_dev->props->power = power; __riva_bl_update_status(info->bl_dev); - up(&info->bl_dev->sem); } mutex_unlock(&info->bl_mutex); @@ -397,11 +395,9 @@ static void riva_bl_init(struct riva_par *par) FB_BACKLIGHT_MAX); mutex_unlock(&info->bl_mutex); - down(&bd->sem); bd->props->brightness = riva_bl_data.max_brightness; bd->props->power = FB_BLANK_UNBLANK; - bd->props->update_status(bd); - up(&bd->sem); + backlight_update_status(bd); #ifdef CONFIG_PMAC_BACKLIGHT mutex_lock(&pmac_backlight_mutex); diff --git a/include/linux/backlight.h b/include/linux/backlight.h index 287c62d..d1426b8 100644 --- a/include/linux/backlight.h +++ b/include/linux/backlight.h @@ -9,8 +9,24 @@ #define _LINUX_BACKLIGHT_H #include +#include #include +/* Notes on locking: + * + * backlight_device->sem is an internal backlight lock protecting the props + * field and no code outside the core should need to touch it. + * + * Access to update_status() is serialised by the update_lock mutex since + * most drivers seem to need this and historically get it wrong. + * + * Most drivers don't need locking on their get_brightness() method. + * If yours does, you need to implement it in the driver. You can use the + * update_lock mutex if appropriate. + * + * Any other use of the locks below is probably wrong. + */ + struct backlight_device; struct fb_info; @@ -44,12 +60,22 @@ struct backlight_device { struct semaphore sem; /* If this is NULL, the backing module is unloaded */ struct backlight_properties *props; + /* Serialise access to update_status method */ + struct mutex update_lock; /* The framebuffer notifier block */ struct notifier_block fb_notif; /* The class device structure */ struct class_device class_dev; }; +static inline void backlight_update_status(struct backlight_device *bd) +{ + mutex_lock(&bd->update_lock); + if (bd->props && bd->props->update_status) + bd->props->update_status(bd); + mutex_unlock(&bd->update_lock); +} + extern struct backlight_device *backlight_device_register(const char *name, struct device *dev,void *devdata,struct backlight_properties *bp); extern void backlight_device_unregister(struct backlight_device *bd); diff --git a/include/linux/lcd.h b/include/linux/lcd.h index 8a468f1..bfbf655 100644 --- a/include/linux/lcd.h +++ b/include/linux/lcd.h @@ -9,8 +9,24 @@ #define _LINUX_LCD_H #include +#include #include +/* Notes on locking: + * + * lcd_device->sem is an internal backlight lock protecting the props + * field and no code outside the core should need to touch it. + * + * Access to set_power() is serialised by the update_lock mutex since + * most drivers seem to need this and historically get it wrong. + * + * Most drivers don't need locking on their get_power() method. + * If yours does, you need to implement it in the driver. You can use the + * update_lock mutex if appropriate. + * + * Any other use of the locks below is probably wrong. + */ + struct lcd_device; struct fb_info; @@ -39,12 +55,22 @@ struct lcd_device { struct semaphore sem; /* If this is NULL, the backing module is unloaded */ struct lcd_properties *props; + /* Serialise access to set_power method */ + struct mutex update_lock; /* The framebuffer notifier block */ struct notifier_block fb_notif; /* The class device structure */ struct class_device class_dev; }; +static inline void lcd_set_power(struct lcd_device *ld, int power) +{ + mutex_lock(&ld->update_lock); + if (ld->props && ld->props->set_power) + ld->props->set_power(ld, power); + mutex_unlock(&ld->update_lock); +} + extern struct lcd_device *lcd_device_register(const char *name, void *devdata, struct lcd_properties *lp); extern void lcd_device_unregister(struct lcd_device *ld); -- 1.8.2.3