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);
+
return 0;
}
--
2.4.6
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