[PATCH v2 5/6] pwm: jz4740: Force TCU2 channels to return to their init level
From: Paul Cercueil
Date: Fri Jun 07 2019 - 12:01:00 EST
When the PWM mode of TCU2 channels is disabled, their corresponding pin
does not always return to its initial level. Force this by using a small
trick: we set duty > period, which is an invalid configuration for the
hardware, which then correctly resets the pin to the initial level.
Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
v2: New patch
drivers/pwm/pwm-jz4740.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-jz4740.c b/drivers/pwm/pwm-jz4740.c
index 75254360621c..f901e8a0d33d 100644
@@ -63,7 +63,15 @@ static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
uint32_t ctrl = jz4740_timer_get_ctrl(pwm->hwpwm);
- /* Disable PWM output.
+ * Set duty > period. This trick allows the TCU channels in TCU2 mode to
+ * properly return to their init level.
+ jz4740_timer_set_duty(pwm->hwpwm, 0xffff);
+ jz4740_timer_set_period(pwm->hwpwm, 0x0);
+ * Disable PWM output.
* In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
* counter is stopped, while in TCU1 mode the order does not matter.