Re: [PATCH v3 07/11] hwmon: chipcap2: enable IRQ processing when regulator is already enabled

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] hwmon: chipcap2: edge-triggered alarms lost for always-on devices
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commit d3d969f96bc4b1b75c3078d08aa3eae3d286d7f8
Author: Javier Carrasco <javier.carrasco.cruz@gmail.com>

hwmon: chipcap2: enable IRQ processing when regulator is already enabled

This commit sets process_irqs to true before returning from cc2_enable()
when the regulator is already enabled. This prevents operations from timing
out by ensuring the ready interrupt is not ignored.

> diff --git a/drivers/hwmon/chipcap2.c b/drivers/hwmon/chipcap2.c
> index 654f6420da7ab..837b1830f2e4e 100644
> --- a/drivers/hwmon/chipcap2.c
> +++ b/drivers/hwmon/chipcap2.c
> @@ -120,8 +120,10 @@ static int cc2_enable(struct cc2_data *data)
>  	int ret;
>  
>  	/* exclusive regulator, check in case a disable failed */
> -	if (regulator_is_enabled(data->regulator))
> +	if (regulator_is_enabled(data->regulator)) {
> +		data->process_irqs = true;
>  		return 0;
> +	}

[Severity: Medium]
While this ensures process_irqs is set to true during cc2_enable() for
always-on regulators, does this fully resolve the missed interrupts?

Looking at cc2_disable() in drivers/hwmon/chipcap2.c, process_irqs is
cleared when the driver becomes idle:

drivers/hwmon/chipcap2.c:cc2_disable() {
    ...
	/* ignore alarms triggered by voltage toggling when powering up */
	data->process_irqs = false;
    ...
}

For always-on regulators, the device remains powered and actively
measuring even when the driver is idle. If an alarm threshold is crossed
during this time, the device will assert the edge-triggered alarm pin
(IRQF_TRIGGER_RISING) high, triggering the interrupt.

Since process_irqs is false, the interrupt handler ignores the edge, and
the pin remains high. Subsequent sysfs reads will call cc2_enable() and
set process_irqs to true, but because the pin is already high, no new
edge is generated.

Patch 9 in this series adds synchronize_irq() to wait for running
handlers, but does this handle new edge interrupts arriving after
process_irqs is set to false?

Are edge-triggered alarms permanently lost for always-on devices because
process_irqs was cleared in cc2_disable()?

>  
>  	/* clear any pending completion */
>  	try_wait_for_completion(&data->complete);

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261014-chipcap2_locks-v3-0-27ebfc2c5b9e@gmail.com?part=7