Re: [PATCH v3 08/11] hwmon: chipcap2: balance regulator state

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] hwmon: permanent timeout when regulator is always-on
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commit 5c82eb519f9635342c52ec29776d87d3ed1c197e
Author: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Subject: hwmon: chipcap2: balance regulator state

This commit adds a regulator_enabled flag to track the regulator state
within the driver, ensuring balanced calls to regulator_enable() and
regulator_disable(). This addresses issues where regulator_is_enabled()
might return unexpected values or when the regulator is configured as
always-on in the device tree.

[Severity: High]
Could this cause a permanent timeout when reading measurements if the device
is connected to an always-on regulator?

In drivers/hwmon/chipcap2.c around line 407, cc2_measurement() expects the
device to automatically start a measurement upon being enabled:

cc2_measurement()
    ret = cc2_enable(data);

If the regulator is marked as always-on in the device tree, the earlier
call to cc2_disable() will successfully drop the regulator reference, but it
will not physically remove power from the chip.

When cc2_enable() is called again, it will see data->regulator_enabled is
false, enable the regulator reference, and return successfully. Because the
chip was never physically power-cycled, it will not initiate an automatic
measurement upon power-on reset.

Since the driver does not explicitly send a measurement command in
cc2_measurement(), the device will never produce new data or fire the ready
interrupt. This appears to cause the wait_for_completion_timeout() call in
cc2_read_measurement() (around line 389) to permanently time out:

    ret = wait_for_completion_timeout(&data->complete, timeout);
    if (!ret)
        return -ETIMEDOUT;

Is there a need to explicitly trigger a measurement command if the regulator
was not actually toggled, or to verify if a power-on reset physically
occurred?

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Sashiko AI review · https://sashiko.dev/#/patchset/20261014-chipcap2_locks-v3-0-27ebfc2c5b9e@gmail.com?part=8