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Commit 4a627b52 authored by Clemens Gruber's avatar Clemens Gruber Committed by Thierry Reding
Browse files

pwm-pca9685: Fix several driver bugs 



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.reding@gmail.com>
Cc: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: default avatarClemens Gruber <clemens.gruber@pqgruber.com>
Signed-off-by: default avatarThierry Reding <thierry.reding@gmail.com>
parent fe0aea79

drivers/pwm/pwm-pca9685.c

+24 −0
Original line number Diff line number Diff line
@@ -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);



	return 0;

}