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authorRyo Kodama <ryo.kodama.vz@renesas.com>2018-03-09 20:24:21 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-04-24 09:36:34 +0200
commitc9b200ce2be5da7613e73daf356bd0ae63c0a48d (patch)
tree88a6d502faa51636b6ecf7f7882725b4160dc627 /drivers/pwm
parentff18ffb1f81db091e916bb3afc4a264219f840ea (diff)
pwm: rcar: Fix a condition to prevent mismatch value setting to duty
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>
Diffstat (limited to 'drivers/pwm')
-rw-r--r--drivers/pwm/pwm-rcar.c8
1 files changed, 6 insertions, 2 deletions
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);