[PATCH] leds: leds-pwm: fix duty time overflow.

[Xiubo Li]

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.
---
 drivers/leds/leds-pwm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index bb6f948..7cb2cd8 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -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);
-- 
1.8.4


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