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.
Fixes: 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of
gpio register")
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Robert Jarzmik <robert.jarz...@free.fr>
---
Since v1: replaced binary ORs with logical ORs after assembly comparison
---
arch/arm/mach-pxa/corgi_pm.c | 8 +++-----
arch/arm/mach-pxa/spitz_pm.c | 5 ++---
2 files changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/arm/mach-pxa/corgi_pm.c b/arch/arm/mach-pxa/corgi_pm.c
index d9206811be9b..8dc39d602884 100644
--- a/arch/arm/mach-pxa/corgi_pm.c
+++ b/arch/arm/mach-pxa/corgi_pm.c
@@ -135,11 +135,9 @@ static unsigned long 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));
+ ret = !gpio_get_value(CORGI_GPIO_AC_IN)
+ || !gpio_get_value(CORGI_GPIO_KEY_INT)
+ || !gpio_get_value(CORGI_GPIO_WAKEUP);
return ret;
}
diff --git a/arch/arm/mach-pxa/spitz_pm.c b/arch/arm/mach-pxa/spitz_pm.c
index ea9f9034cb54..dd85869f6f99 100644
--- a/arch/arm/mach-pxa/spitz_pm.c
+++ b/arch/arm/mach-pxa/spitz_pm.c
@@ -168,9 +168,8 @@ static int spitz_should_wakeup(unsigned int resume_on_alarm)
static unsigned long 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));
+ ret = !gpio_get_value(SPITZ_GPIO_KEY_INT)
+ || gpio_get_value(SPITZ_GPIO_SYNC);
return ret;
}
--
2.1.4
