Robert Jarzmik <robert.jarz...@free.fr> writes:
> 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.
>
> Fixes: 9bf448c66d4b ("ARM: pxa: use generic gpio operation instead of
> gpio register")
> Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
> Cc: Joe Perches <j...@perches.com>
> Signed-off-by: Robert Jarzmik <robert.jarz...@free.fr>
Queued into pxa/for-next.
--
Robert
