diff options
| author | Marek Vasut <marex@denx.de> | 2023-05-12 18:47:36 +0200 |
|---|---|---|
| committer | Thierry Reding <thierry.reding@gmail.com> | 2023-06-23 15:42:58 +0200 |
| commit | 38ba83598633373f47951384cfc389181c8d1bed (patch) | |
| tree | 2fb81ddfbdd1b4aa45fb67aa6e7679ca576e19c1 /drivers/pwm | |
| parent | 661dfb7f46298e53f6c3deaa772fa527aae86193 (diff) | |
| download | lwn-38ba83598633373f47951384cfc389181c8d1bed.tar.gz lwn-38ba83598633373f47951384cfc389181c8d1bed.zip | |
pwm: sysfs: Do not apply state to already disabled PWMs
If the PWM is exported but not enabled, do not call pwm_class_apply_state().
First of all, in this case, period may still be unconfigured and this would
make pwm_class_apply_state() return -EINVAL, and then suspend would fail.
Second, it makes little sense to apply state onto PWM that is not enabled
before suspend.
Failing case:
"
$ echo 1 > /sys/class/pwm/pwmchip4/export
$ echo mem > /sys/power/state
...
pwm pwmchip4: PM: dpm_run_callback(): pwm_class_suspend+0x1/0xa8 returns -22
pwm pwmchip4: PM: failed to suspend: error -22
PM: Some devices failed to suspend, or early wake event detected
"
Working case:
"
$ echo 1 > /sys/class/pwm/pwmchip4/export
$ echo 100 > /sys/class/pwm/pwmchip4/pwm1/period
$ echo 10 > /sys/class/pwm/pwmchip4/pwm1/duty_cycle
$ echo mem > /sys/power/state
...
"
Do not call pwm_class_apply_state() in case the PWM is disabled
to fix this issue.
Fixes: 7fd4edc57bbae ("pwm: sysfs: Add suspend/resume support")
Signed-off-by: Marek Vasut <marex@denx.de>
Fixes: ef2bf4997f7d ("pwm: Improve args checking in pwm_apply_state()")
Reviewed-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
Diffstat (limited to 'drivers/pwm')
| -rw-r--r-- | drivers/pwm/sysfs.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c index 1a106ec32939..8d1254761e4d 100644 --- a/drivers/pwm/sysfs.c +++ b/drivers/pwm/sysfs.c @@ -424,6 +424,13 @@ static int pwm_class_resume_npwm(struct device *parent, unsigned int npwm) if (!export) continue; + /* If pwmchip was not enabled before suspend, do nothing. */ + if (!export->suspend.enabled) { + /* release lock taken in pwm_class_get_state */ + mutex_unlock(&export->lock); + continue; + } + state.enabled = export->suspend.enabled; ret = pwm_class_apply_state(export, pwm, &state); if (ret < 0) @@ -448,7 +455,17 @@ static int pwm_class_suspend(struct device *parent) if (!export) continue; + /* + * If pwmchip was not enabled before suspend, save + * state for resume time and do nothing else. + */ export->suspend = state; + if (!state.enabled) { + /* release lock taken in pwm_class_get_state */ + mutex_unlock(&export->lock); + continue; + } + state.enabled = false; ret = pwm_class_apply_state(export, pwm, &state); if (ret < 0) { |