Patch "ARM: pxa: fix GPIO double shifts" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

ARM: pxa: fix GPIO double shifts

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arm-pxa-fix-gpio-double-shifts.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Robert Jarzmik <[email protected]>
Date: Tue, 2 Aug 2016 00:01:32 +0200
Subject: ARM: pxa: fix GPIO double shifts

From: Robert Jarzmik <[email protected]>

commit ca26475bf02ed8562b9b46f91d3e8b52ec312541 upstream.

The commit 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of gpio register") from Oct 17, 2011, leads to the following static checker warning:
arch/arm/mach-pxa/spitz_pm.c:172 spitz_charger_wakeup()
warn: double left shift '!gpio_get_value(SPITZ_GPIO_KEY_INT)

        << (1 << ((SPITZ_GPIO_KEY_INT) & 31))'

As Dan reported, the value is shifted three times :
- once by gpio_get_value(), which returns either 0 or BIT(gpio)
- once by the shift operation '<<'
- a last time by GPIO_bit(gpio) which is BIT(gpio)

Therefore the calculation lead to a chained or operator of :
- (1 << gpio) << (1 << gpio) = (2^gpio)^gpio = 2 ^ (gpio * gpio)

It is be sheer luck the former statement works, only because each gpio used is strictly smaller than 6, and therefore 2^(gpio^2) never overflows a 32 bits value, and because it is used as a boolean value to check a gpio activation.

As the xxx_charger_wakeup() functions are used as a true/false detection mechanism, take that opportunity to change their prototypes from integer return value to boolean one.

gpio register")

---
 arch/arm/mach-pxa/corgi_pm.c   |   13 ++++---------
 arch/arm/mach-pxa/sharpsl_pm.c |    2 +-
 arch/arm/mach-pxa/sharpsl_pm.h |    2 +-
 arch/arm/mach-pxa/spitz_pm.c   |    9 +++------
 4 files changed, 9 insertions(+), 17 deletions(-)

@@ -131,16 +131,11 @@ static int corgi_should_wakeup(unsigned
 	return is_resume;
 }
 
-static unsigned long corgi_charger_wakeup(void)
+static bool corgi_charger_wakeup(void)
 {
-	unsigned long ret;
-
-	ret = (!gpio_get_value(CORGI_GPIO_AC_IN) << GPIO_bit(CORGI_GPIO_AC_IN))
-		| (!gpio_get_value(CORGI_GPIO_KEY_INT)
-		<< GPIO_bit(CORGI_GPIO_KEY_INT))
-		| (!gpio_get_value(CORGI_GPIO_WAKEUP)
-		<< GPIO_bit(CORGI_GPIO_WAKEUP));
-	return ret;
+	return !gpio_get_value(CORGI_GPIO_AC_IN) ||
+		!gpio_get_value(CORGI_GPIO_KEY_INT) ||
+		!gpio_get_value(CORGI_GPIO_WAKEUP);
 }
 
 unsigned long corgipm_read_devdata(int type)

@@ -744,7 +744,7 @@ static int sharpsl_off_charge_battery(vo
 		time = RCNR;
 		while (1) {
 			/* Check if any wakeup event had occurred */
-			if (sharpsl_pm.machinfo->charger_wakeup() != 0)
+			if (sharpsl_pm.machinfo->charger_wakeup())
 				return 0;
 			/* Check for timeout */
 			if ((RCNR - time) > SHARPSL_WAIT_CO_TIME)

@@ -34,7 +34,7 @@ struct sharpsl_charger_machinfo {
 #define SHARPSL_STATUS_LOCK     5
 #define SHARPSL_STATUS_CHRGFULL 6
 #define SHARPSL_STATUS_FATAL    7
-	unsigned long (*charger_wakeup)(void);
+	bool (*charger_wakeup)(void);
 	int (*should_wakeup)(unsigned int resume_on_alarm);
 	void (*backlight_limit)(int);
 	int (*backlight_get_status) (void);

@@ -165,13 +165,10 @@ static int spitz_should_wakeup(unsigned
 	return is_resume;
 }
 
-static unsigned long spitz_charger_wakeup(void)
+static bool spitz_charger_wakeup(void)
 {
-	unsigned long ret;
-	ret = ((!gpio_get_value(SPITZ_GPIO_KEY_INT)
-		<< GPIO_bit(SPITZ_GPIO_KEY_INT))
-		| gpio_get_value(SPITZ_GPIO_SYNC));
-	return ret;
+	return !gpio_get_value(SPITZ_GPIO_KEY_INT) ||
+		gpio_get_value(SPITZ_GPIO_SYNC);
 }
 
 unsigned long spitzpm_read_devdata(int type)

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/arm-pxa-pxa_cplds-fix-interrupt-handling.patch queue-4.8/arm-pxa-fix-gpio-double-shifts.patch