The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6225f9c64b40bc8a22503e9cda70f55d7a9dd3c6 Mon Sep 17 00:00:00 2001
From: Ryo Kodama ryo.kodama.vz@renesas.com Date: Fri, 9 Mar 2018 20:24:21 +0900 Subject: [PATCH] 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: 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
diff --git a/drivers/pwm/pwm-rcar.c b/drivers/pwm/pwm-rcar.c index 1c85ecc9e7ac..0fcf94ffad32 100644 --- a/drivers/pwm/pwm-rcar.c +++ b/drivers/pwm/pwm-rcar.c @@ -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);