Re: [PATCH regression fix] misc: lis3lv02d_i2c: Fix regulators getting en-/dis-abled twice on suspend/resume

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Dear Hans,


Thank you for the patch.

Am 20.02.24 um 20:00 schrieb Hans de Goede:
When not configured for wakeup lis3lv02d_i2c_suspend() will call
lis3lv02d_poweroff() even if the device has already been turned off
by the runtime-suspend handler and if configured for wakeup and
the device is runtime-suspended at this point then it is not turned
back on to serve as a wakeup source.

Before commit b1b9f7a49440 ("misc: lis3lv02d_i2c: Add missing setting
of the reg_ctrl callback"), lis3lv02d_poweroff() failed to disable
the regulators which as a side effect made calling poweroff() twice ok.

Now that poweroff() correctly disables the regulators, doing this twice
triggers a WARN() in the regulator core:

unbalanced disables for regulator-dummy
WARNING: CPU: 1 PID: 92 at drivers/regulator/core.c:2999 _regulator_disable
...

Fix lis3lv02d_i2c_suspend() to not call poweroff() a second time if
already runtime-suspended and add a poweron() call when necessary to
make wakeup work.

lis3lv02d_i2c_resume() has similar issues, with an added weirness that
it always powers on the device if it is runtime suspended, after which
the first runtime-resume will call poweron() again, causing the enabled
count for the regulator to increase by 1 every suspend/resume. These
unbalanced regulator_enable() calls cause the regulator to never
be turned off and trigger the following WARN() on driver unbind:

WARNING: CPU: 1 PID: 1724 at drivers/regulator/core.c:2396 _regulator_put

Fix this by making lis3lv02d_i2c_resume() mirror the new suspend().

Fixes: b1b9f7a49440 ("misc: lis3lv02d_i2c: Add missing setting of the reg_ctrl callback")
Reported-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
Closes: https://lore.kernel.org/regressions/5fc6da74-af0a-4aac-b4d5-a000b39a63a5@xxxxxxxxxxxxx/
Cc: stable@xxxxxxxxxxxxxxx
Cc: regressions@xxxxxxxxxxxxxxx
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
  drivers/misc/lis3lv02d/lis3lv02d_i2c.c | 21 +++++++++++++--------
  1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/lis3lv02d/lis3lv02d_i2c.c b/drivers/misc/lis3lv02d/lis3lv02d_i2c.c
index c6eb27d46cb0..15119584473c 100644
--- a/drivers/misc/lis3lv02d/lis3lv02d_i2c.c
+++ b/drivers/misc/lis3lv02d/lis3lv02d_i2c.c
@@ -198,8 +198,14 @@ static int lis3lv02d_i2c_suspend(struct device *dev)
  	struct i2c_client *client = to_i2c_client(dev);
  	struct lis3lv02d *lis3 = i2c_get_clientdata(client);
- if (!lis3->pdata || !lis3->pdata->wakeup_flags)
+	/* Turn on for wakeup if turned off by runtime suspend */
+	if (lis3->pdata && lis3->pdata->wakeup_flags) {
+		if (pm_runtime_suspended(dev))
+			lis3lv02d_poweron(lis3);
+	/* For non wakeup turn off if not already turned off by runtime suspend */
+	} else if (!pm_runtime_suspended(dev))
  		lis3lv02d_poweroff(lis3);
+
  	return 0;
  }
@@ -208,13 +214,12 @@ static int lis3lv02d_i2c_resume(struct device *dev)
  	struct i2c_client *client = to_i2c_client(dev);
  	struct lis3lv02d *lis3 = i2c_get_clientdata(client);
- /*
-	 * pm_runtime documentation says that devices should always
-	 * be powered on at resume. Pm_runtime turns them off after system
-	 * wide resume is complete.
-	 */
-	if (!lis3->pdata || !lis3->pdata->wakeup_flags ||
-		pm_runtime_suspended(dev))
+	/* Turn back off if turned on for wakeup and runtime suspended*/
+	if (lis3->pdata && lis3->pdata->wakeup_flags) {
+		if (pm_runtime_suspended(dev))
+			lis3lv02d_poweroff(lis3);
+	/* For non wakeup turn back on if not runtime suspended */
+	} else if (!pm_runtime_suspended(dev))
  		lis3lv02d_poweron(lis3);
return 0;

I applied this commit on top of Linus’ master branch, and successfully tested with S0ix and ACPI S3, that the warning is gone.

Tested-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx> # Dell XPS 15 7590

Looking at the diff, this also looks good. Thank you for writing the helpful commit message.

Reviewed-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>

Thank you for addressing this so quickly, and sorry for the late reply.


Kind regards,

Paul




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