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pwm: jz4740: Force TCU2 channels to return to their init level

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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@crapouillou.net>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Paul Cercueil 2019-06-07 17:44:09 +02:00 committed by Thierry Reding
parent 1ac99c58bd
commit 6580fd1730
1 changed files with 9 additions and 1 deletions
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10
drivers/pwm/pwm-jz4740.c
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@ -72,7 +72,15 @@ 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.
*/