[PATCH 6.4 647/800] pwm: sysfs: Do not apply state to already disabled PWMs

Greg Kroah-Hartman
2023-07-16T20:23:08Z

From: Marek Vasut <marex@denx.de>

[ 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@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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pwm/sysfs.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)

diff --git a/drivers/pwm/sysfs.c b/drivers/pwm/sysfs.c
index 1a106ec329392..8d1254761e4dd 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) {
--
2.39.2