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ARM: pxa: fix GPIO double shifts

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The commit 9bf448c66d ("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: 9bf448c66d ("ARM: pxa: use generic gpio operation instead of
gpio register")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
This commit is contained in:
Robert Jarzmik
2016-08-02 00:01:32 +02:00
parent cd0f319bfb
commit ca26475bf0
4 changed files with 9 additions and 17 deletions
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2
arch/arm/mach-pxa/sharpsl_pm.c
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@@ -744,7 +744,7 @@ static int sharpsl_off_charge_battery(void)
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)