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

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

arch/powerpc/kernel/traps.c

+1 −3
Original line number Diff line number Diff line
@@ -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

arch/powerpc/platforms/powermac/backlight.c

+5 −14
Original line number Diff line number Diff line
@@ -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);

drivers/macintosh/via-pmu-backlight.c

+1 −3
Original line number Diff line number Diff line
@@ -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)

drivers/misc/asus-laptop.c

+5 −15
Original line number Diff line number Diff line
@@ -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);

		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);

		backlight_update_status(bd);

	}

	return 0;

}

drivers/usb/misc/appledisplay.c

+0 −6
Original line number Diff line number Diff line
@@ -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);