Re: [PATCH] Input: elan_i2c - Fix regulator enable count imbalance after suspend/resume

Hi,

On 1/6/22 07:50, Jingle.Wu wrote:

Hi Hans/Dmitry:

It is not OK to skip elan_enable_power() for all Elan touchpad controllers.

I suggest to deal with this touchpad module ID as "quirk" case to support
this special case.

There is nothing special / quirky about this, regulator enable imbalances
simply must not happen / must be fixed.

I'll prepare a new version of the patch which adds a parameter to
elan_enable_power() to skip the regulator enable if the regulator
was not disabled on suspend.

This will allow still always calling elan_enable_power() on resume,
while also fixing the regulator imbalance.

Note that this will also help save power, the regulator imbalance
also means that the regulator will no longer get disabled _ever_
after the first suspend/resume cycle where device_may_wakeup()
returns true.

Regards,

Hans

-----Original Message-----
From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com] 
Sent: Tuesday, January 4, 2022 8:30 AM
To: Hans de Goede <redacted>
Cc: Jingle Wu <redacted>; linux-input@vger.kernel.org
Subject: Re: [PATCH] Input: elan_i2c - Fix regulator enable count imbalance
after suspend/resume

Hi Hans,

On Wed, Dec 22, 2021 at 11:06:41PM +0100, Hans de Goede wrote:

quoted

Before these changes elan_suspend() would only call 
elan_disable_power() when device_may_wakeup() returns false; whereas 
elan_resume() would unconditionally call elan_enable_power(), leading 
to an enable count imbalance when device_may_wakeup() returns true.

This triggers the "WARN_ON(regulator->enable_count)" in 
regulator_put() when the elan_i2c driver gets unbound, this happens 
e.g. with the hot-plugable dock with Elan I2C touchpad for the Asus TF103C

2-in-1.

quoted

Fix this by making the elan_enable_power() call also be conditional on 
device_may_wakeup() returning false.

elan_enable_power() not only tries to toggle the regulator, but also tries
to issue command to the controller to power/wake it up. I need confirmation
from Jingle Wu that skipping this is OK for all Elan touchpad controllers,
or if we need to add call to either power control or sleep control method to
make sure the controller it fully resumed.

Jingle, what can you tell us here?

quoted

Signed-off-by: Hans de Goede <redacted>
---
 drivers/input/mouse/elan_i2c_core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/input/mouse/elan_i2c_core.c 

b/drivers/input/mouse/elan_i2c_core.c
index 47af62c12267..cdb36d35ffa4 100644

--- a/drivers/input/mouse/elan_i2c_core.c
+++ b/drivers/input/mouse/elan_i2c_core.c

@@ -1412,17 +1412,17 @@ static int __maybe_unused elan_resume(struct

device *dev)

quoted

 	struct elan_tp_data *data = i2c_get_clientdata(client);
 	int error;
 
-	if (device_may_wakeup(dev) && data->irq_wake) {
+	if (!device_may_wakeup(dev)) {
+		error = elan_enable_power(data);
+		if (error) {
+			dev_err(dev, "power up when resuming failed: %d\n",

error);

quoted

+			goto err;
+		}
+	} else if (data->irq_wake) {
 		disable_irq_wake(client->irq);
 		data->irq_wake = false;
 	}
 
-	error = elan_enable_power(data);
-	if (error) {
-		dev_err(dev, "power up when resuming failed: %d\n", error);
-		goto err;
-	}
-
 	error = elan_initialize(data, data->quirks &

ETP_QUIRK_QUICK_WAKEUP);

quoted

 	if (error)
 		dev_err(dev, "initialize when resuming failed: %d\n",

error);

quoted

--
2.33.1

Thanks.