Messages in this thread | | | Date | Sun, 29 Sep 2013 18:12:05 +0800 | From | Bo Shen <> | Subject | Re: [PATCH] PWM: atmel-pwm: use request/free instead of enable/disable |
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Hi Alexandre,
On 9/28/2013 04:10, Alexandre Belloni wrote: > I found that disabling a pwm while it is at a low level will actually put it > back at a high level. The main symptom is that leds-pwm is calling pwm_disable() > after setting the duty cycle to 0. Hence, instead of getting a switched off LED, > you get an LED lit up at full brightness. > > Solve that by using the request and free callbacks to enable and disable the > pwm channels and the clock. > > Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com> > --- > > This patch applies after: > [PATCH v4] PWM: atmel-pwm: add PWM controller driver > > drivers/pwm/pwm-atmel.c | 14 +++++--------- > 1 file changed, 5 insertions(+), 9 deletions(-) > > diff --git a/drivers/pwm/pwm-atmel.c b/drivers/pwm/pwm-atmel.c > index 6af7a50..4526e71 100644 > --- a/drivers/pwm/pwm-atmel.c > +++ b/drivers/pwm/pwm-atmel.c > @@ -209,7 +209,7 @@ static int atmel_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, > return 0; > } > > -static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) > +static int atmel_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm) > { > struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); > int ret; > @@ -225,23 +225,19 @@ static int atmel_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm) > return 0; > } > > -static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm) > +static void atmel_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) > { > struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip); > - u32 val; > > atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm); > - > - val = atmel_pwm_readl(atmel_pwm, PWM_SR); > - if ((val & PWM_SR_ALL_CH_ON) == 0) > - clk_disable(atmel_pwm->clk); > + clk_disable(atmel_pwm->clk); > } > > static const struct pwm_ops atmel_pwm_ops = { > .config = atmel_pwm_config, > .set_polarity = atmel_pwm_set_polarity, > - .enable = atmel_pwm_enable, > - .disable = atmel_pwm_disable, > + .request = atmel_pwm_request, > + .free = atmel_pwm_free,
This will cause pwmadd_chip failure.
Code from <drivers/pwm/core.c>, in function: pwmadd_chip() ---8>--- if (!chip || !chip->dev || !chip->ops || !chip->ops->config || !chip->ops->enable || !chip->ops->disable) return -EINVAL; ---<8---
> .owner = THIS_MODULE, > }; >
Best Regards, Bo Shen
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