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pwm: atmel: Fix disabling of PWM channels 

When disabling a PWM channel, the PWM clock was being stopped
immediately after writing to PWM_DIS. As a result, the disabling
of the PWM channel did not complete properly, and the PWM output
might be left at the wrong level.

Fix this by waiting for the channel to be effectively disabled
(by checking the PWM_SR register) before disabling the clock.

Signed-off-by: Guillermo Rodriguez <guille.rodriguez@gmail.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
hifive-unleashed-5.1
Guillermo Rodriguez 2016-05-13 13:09:37 +02:00 committed by Thierry Reding
parent 396d502c51
commit f718c54c1a
1 changed files with 10 additions and 0 deletions
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10
drivers/pwm/pwm-atmel.c
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@ -271,6 +271,16 @@ static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
mutex_unlock(&atmel_pwm->isr_lock);
atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
/*
* Wait for the PWM channel disable operation to be effective before
* stopping the clock.
*/
timeout = jiffies + 2 * HZ;
while ((atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) &&
time_before(jiffies, timeout))
usleep_range(10, 100);
clk_disable(atmel_pwm->clk);
}