Commit 6225f9c6 authored Mar 09, 2018 by Ryo Kodama Committed by Thierry Reding Mar 28, 2018

pwm: rcar: Fix a condition to prevent mismatch value setting to duty



This patch fixes an issue that is possible to set mismatch value to duty
for R-Car PWM if we input the following commands:

 # cd /sys/class/pwm/<pwmchip>/
 # echo 0 > export
 # cd pwm0
 # echo 30 > period
 # echo 30 > duty_cycle
 # echo 0 > duty_cycle
 # cat duty_cycle
 0
 # echo 1 > enable
 --> Then, the actual duty_cycle is 30, not 0.

So, this patch adds a condition into rcar_pwm_config() to fix this
issue.

Signed-off-by: Ryo Kodama <ryo.kodama.vz@renesas.com>
[shimoda: revise the commit log and add Fixes and Cc tags]
Fixes: ed6c1476 ("pwm: Add support for R-Car PWM Timer")
Cc: Cc: <stable@vger.kernel.org> # v4.4+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

parent 8bbf5b42

drivers/pwm/pwm-rcar.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -156,8 +156,12 @@ static int rcar_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
		if (div < 0)
		return div;

		/* Let the core driver set pwm->period if disabled and duty_ns == 0 */
		if (!pwm_is_enabled(pwm) && !duty_ns)
		/*
		* Let the core driver set pwm->period if disabled and duty_ns == 0.
		* But, this driver should prevent to set the new duty_ns if current
		* duty_cycle is not set
		*/
		if (!pwm_is_enabled(pwm) && !duty_ns && !pwm->state.duty_cycle)
		return 0;

		rcar_pwm_update(rp, RCAR_PWMCR_SYNC, RCAR_PWMCR_SYNC, RCAR_PWMCR);

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