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? Thierry
signature.asc
Description: PGP signature
