Messages in this thread | | | Date | Fri, 14 Mar 2014 15:54:09 +0100 | From | Nicolas Ferre <> | Subject | Re: [PATCH 2/2] PWM: atmel: correct CDTY calculation |
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On 14/03/2014 15:19, Alexandre Belloni : >>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>
> --- > drivers/pwm/pwm-atmel.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c > index 2d69e9c431dd..0adc952cc4ef 100644 > --- a/drivers/pwm/pwm-atmel.c > +++ b/drivers/pwm/pwm-atmel.c > @@ -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) { >
-- Nicolas Ferre
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