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Date: Wed, 11 Dec 2013 17:19:42 +0800 From: Xiubo Li <Li.Xiubo@...escale.com> To: <cooloney@...il.com>, <rpurdie@...ys.net>, <linux-leds@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <b47053@...escale.com> Subject: [PATCH] leds: leds-pwm: fix duty time overflow. 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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