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

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commit 6225f9c64b40bc8a22503e9cda70f55d7a9dd3c6 upstream.

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: ed6c1476bf7f ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ryo Kodama 2018-03-09 20:24:21 +09:00 committed by Greg Kroah-Hartman
parent 6af2423153
commit f6ed0ff4c7
1 changed files with 6 additions and 2 deletions
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8
drivers/pwm/pwm-rcar.c
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@ -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);