This is a note to let you know that I've just added the patch titled
pwm: sysfs: Do not apply state to already disabled PWMs
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pwm-sysfs-do-not-apply-state-to-already-disabled-pwm.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit fa6912a8dd82c69bf7e1b9dda0dc7ce9cc0170fe
Author: Marek Vasut <marex@xxxxxxx>
Date: Fri May 12 18:47:36 2023 +0200
pwm: sysfs: Do not apply state to already disabled PWMs
[ Upstream commit 38ba83598633373f47951384cfc389181c8d1bed ]
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@xxxxxxx>
Fixes: ef2bf4997f7d ("pwm: Improve args checking in pwm_apply_state()")
Reviewed-by: Brian Norris <briannorris@xxxxxxxxxxxx>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 2389b86698468..986f3a29a13d5 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 __maybe_unused 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) {
