From 4a627b52e47ee09348773a981f2097f69ff349ee Mon Sep 17 00:00:00 2001 From: Clemens Gruber Date: Thu, 23 Jul 2015 17:19:01 +0200 Subject: [PATCH] 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 Cc: Steffen Trumtrar Signed-off-by: Clemens Gruber Signed-off-by: Thierry Reding --- 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 bd5f027..0d17d99 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); + return 0; } -- 2.7.4