lkml.org 
[lkml]   [2016]   [May]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] pwm: don't allow duty cycle higher than period
Date
It doesn't make sense to allow the duty cycle to be larger than the
period. I can see this behavior by, e.g.:

# echo 1 > /sys/class/pwm/pwmchip0/export
# cat /sys/class/pwm/pwmchip0/pwm1/period
100
# echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle
[... driver may or may not reject the value, or trigger some logic bug ...]

It's better to see:

# echo 1 > /sys/class/pwm/pwmchip0/export
# cat /sys/class/pwm/pwmchip0/pwm1/period
100
# echo 101 > /sys/class/pwm/pwmchip0/pwm1/duty_cycle
-bash: echo: write error: Invalid argument

Signed-off-by: Brian Norris <briannorris@chromium.org>
---
drivers/pwm/core.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index dba3843c53b8..9246b60f894a 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -463,6 +463,9 @@ int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)
if (!memcmp(state, &pwm->state, sizeof(*state)))
return 0;

+ if (state->duty_cycle > state->period)
+ return -EINVAL;
+
if (pwm->chip->ops->apply) {
err = pwm->chip->ops->apply(pwm->chip, pwm, state);
if (err)
--
2.8.0.rc3.226.g39d4020
\
 
 \ /
  Last update: 2016-05-26 23:21    [W:0.236 / U:0.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site