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leds: leds-pwm: fix duty time overflow.

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Overflow maybe occurs when calculates the duty time. For instance,
the period time is 990000000ns, and the max_brightness is 127, when
setting the brightness to 12, the duty value will be 25906026ns, but
it should be 93543307ns.

Signed-off-by: Bryan Wu <cooloney@gmail.com>
This commit is contained in:
Xiubo Li 2013-12-11 01:19:42 -08:00 committed by Bryan Wu
parent 3df22c06b9
commit fc1aee038b
1 changed files with 4 additions and 2 deletions
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6
drivers/leds/leds-pwm.c
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@ -66,9 +66,11 @@ static void led_pwm_set(struct led_classdev *led_cdev,
struct led_pwm_data *led_dat =
container_of(led_cdev, struct led_pwm_data, cdev);
unsigned int max = led_dat->cdev.max_brightness;
unsigned int period = led_dat->period;
unsigned long long duty = led_dat->period;
led_dat->duty = brightness * period / max;
duty *= brightness;
do_div(duty, max);
led_dat->duty = duty;
if (led_dat->can_sleep)
schedule_work(&led_dat->work);