4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ryo Kodama <ryo.kodama.vz@xxxxxxxxxxx>
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@xxxxxxxxxxx>
[shimoda: revise the commit log and add Fixes and Cc tags]
Fixes: ed6c1476bf7f ("pwm: Add support for R-Car PWM Timer")
Cc: Cc: <stable@xxxxxxxxxxxxxxx> # v4.4+
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/pwm/pwm-rcar.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/pwm/pwm-rcar.c
+++ b/drivers/pwm/pwm-rcar.c
@@ -156,8 +156,12 @@ static int rcar_pwm_config(struct pwm_ch
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);