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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: Clemens Gruber <clemens.gruber@pqgruber.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
hifive-unleashed-5.1
Clemens Gruber 2015-07-23 17:19:01 +02:00 committed by Thierry Reding
parent fe0aea7978
commit 4a627b52e4
1 changed files with 24 additions and 0 deletions
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24
drivers/pwm/pwm-pca9685.c
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@ -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;
}