Commit 28ee086d authored by Richard Purdie's avatar Richard Purdie

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: default avatarRichard Purdie <rpurdie@rpsys.net>
parent a8db3c19
......@@ -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
......
......@@ -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);
......
......@@ -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)
......
......@@ -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;
}
......
......@@ -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);
......
......@@ -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);
......
......@@ -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);
......
......@@ -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);
......
......@@ -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));
......
......@@ -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;
......
......@@ -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 */
......
......@@ -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);
......
......@@ -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);
......
......@@ -9,8 +9,24 @@
#define _LINUX_BACKLIGHT_H
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
/* 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);
......
......@@ -9,8 +9,24 @@
#define _LINUX_LCD_H
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
/* 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);
......
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