| Message ID | 1394806749-29778-3-git-send-email-alexandre.belloni@free-electrons.com |
|---|---|
| State | Accepted |
| Headers | show |
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) { >
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) {
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> --- drivers/pwm/pwm-atmel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)