On Mon, Jul 20, 2015 at 11:27:23AM +0200, Thierry Reding wrote:
> On Mon, Jul 20, 2015 at 10:36:08AM +0200, Clemens Gruber wrote:
> > Problems:
> > - When duty_ns == period_ns, the full OFF bit was not cleared and the
> > PWM output of the PCA9685 stayed off.
> > - When duty_ns == period_ns and the catch-all channel was used, the
> > ALL_LED_OFF_L register was not cleared.
> > - The full ON bit was not cleared when setting the OFF time, therefore
> > the exact OFF time was ignored when setting a duty_ns < period_ns
> >
> > Solution: Clear both OFF registers when setting full ON and clear the
> > full ON bit when changing the OFF registers.
> >
> > Cc: Thierry Reding <thierry.red...@gmail.com>
> > Cc: Steffen Trumtrar <s.trumt...@pengutronix.de>
> > Signed-off-by: Clemens Gruber <clemens.gru...@pqgruber.com>
> > ---
> > drivers/pwm/pwm-pca9685.c | 24 ++++++++++++++++++++++++
> > 1 file changed, 24 insertions(+)
> >
> > diff --git a/drivers/pwm/pwm-pca9685.c b/drivers/pwm/pwm-pca9685.c
> > index 34b5c27..f4a9c4a 100644
> > --- a/drivers/pwm/pwm-pca9685.c
> > +++ b/drivers/pwm/pwm-pca9685.c
> > @@ -85,6 +85,22 @@ static int pca9685_pwm_config(struct pwm_chip *chip,
> > struct pwm_device *pwm,
> > }
> >
> > if (duty_ns == period_ns) {
> > + /* Clear both OFF registers */
> > + if (pwm->hwpwm >= PCA9685_MAXCHAN)
> > + reg = PCA9685_ALL_LED_OFF_L;
> > + else
> > + reg = LED_N_OFF_L(pwm->hwpwm);
> > +
> > + regmap_write(pca->regmap, reg, 0x0);
> > +
> > + if (pwm->hwpwm >= PCA9685_MAXCHAN)
> > + reg = PCA9685_ALL_LED_OFF_H;
> > + else
> > + reg = LED_N_OFF_H(pwm->hwpwm);
> > +
> > + regmap_write(pca->regmap, reg, 0x0);
> > +
> > + /* Set the full ON bit */
> > if (pwm->hwpwm >= PCA9685_MAXCHAN)
> > reg = PCA9685_ALL_LED_ON_H;
> > else
> > @@ -112,6 +128,14 @@ static int pca9685_pwm_config(struct pwm_chip *chip,
> > struct pwm_device *pwm,
> >
> > regmap_write(pca->regmap, reg, ((int)duty >> 8) & 0xf);
> >
> > + /* Clear the full ON bit, otherwise the set OFF time has no effect */
> > + if (pwm->hwpwm >= PCA9685_MAXCHAN)
> > + reg = PCA9685_ALL_LED_ON_H;
> > + else
> > + reg = LED_N_ON_H(pwm->hwpwm);
> > +
> > + regmap_write(pca->regmap, reg, 0);
>
> Doesn't this undo the setting of this register back up in the duty_ns ==
> period_ns conditional block?Nevermind, looking at the full driver code I see that the branch returns 0. Thierry
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