Commit 916030db authored Mar 14, 2014 by Alexandre Belloni Committed by Thierry Reding Mar 18, 2014

pwm: atmel: correct CDTY calculation



From the datasheet, the actual duty cycle is:

	(period - (1 / clk) * CDTY) / period

This actually correct the polarity of the PWM and solves the issue that
pwm-leds exhibits: when setting a duty cycle of 0 and then disabling a
channel, the level was wrong (1 when the polarity was normal and 0 when
the polarity was inversed).

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

parent 8db9e29f

drivers/pwm/pwm-atmel.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -133,7 +133,7 @@ static int atmel_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
		prd = div;
		div *= duty_ns;
		do_div(div, period_ns);
		dty = div;
		dty = prd - div;

		ret = clk_enable(atmel_pwm->clk);
		if (ret) {