Re: [PATCH] HID: i2c-hid-acpi: restore touchscreen IRQ routing on HP OmniBook X Flip 16

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] hid: i2c-hid-acpi: IRQ routing quirk bypassed on resume if wakeup enabled
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commit c1ea0adbfc4956d2ccd0cfccdc56448c010e7ac2
Author: Waqar Gulzar <iamwaqargulzar@gmail.com>

HID: i2c-hid-acpi: restore touchscreen IRQ routing on HP OmniBook X Flip 16

The HP OmniBook X Flip 16 firmware disconnects the ELAN2514 touchscreen
interrupt from the IO-APIC in its power resource _ON method, which Linux
runs at probe and resume. This patch re-enables the routing through the
firmware's own helper from i2c-hid-acpi's power_up hook.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2142384
Link: https://github.com/testyfishy/hp-omnibook-flip16-touchscreen-fix
Link: https://github.com/iamwaqargulzar/hp-omnibook-x-flip-16-linux-touchscreen-pen-fix

> diff --git a/drivers/hid/i2c-hid/i2c-hid-acpi.c b/drivers/hid/i2c-hid/i2c-hid-acpi.c
> index 9371db200fc4d..b6348ee3d422b 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-acpi.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-acpi.c

[ ... ]

> @@ -85,6 +140,9 @@ static int i2c_hid_acpi_probe(struct i2c_client *client)
>  	ihid_acpi->adev = adev;
>  	ihid_acpi->ops.shutdown_tail = i2c_hid_acpi_shutdown_tail;
>  	ihid_acpi->ops.restore_sequence = i2c_hid_acpi_restore_sequence;
> +	if (acpi_dev_hid_uid_match(ihid_acpi->adev, "ELAN2514", NULL) &&
> +	    dmi_check_system(i2c_hid_acpi_irq_route_dmi))
> +		ihid_acpi->ops.power_up = i2c_hid_acpi_restore_irq_route;

[Severity: Medium]
Will this quirk be reliably applied on resume if the device has wakeup enabled?

The quirk is hooked up to the power_up callback. However, in
i2c_hid_core_resume() the core driver conditionally skips the power_up
callback if wakeup is enabled:

drivers/hid/i2c-hid/i2c-hid-core.c:i2c_hid_core_resume() {
    ...
	if (!device_may_wakeup(&client->dev))
		i2c_hid_core_power_up(ihid);
    ...
}

If the user or system enables wakeup for the touchscreen,
i2c_hid_core_resume() skips i2c_hid_core_power_up(). If the device's ACPI
power resource was turned off during sleep, _ON will execute on resume and
break the IRQ routing again, but the power_up quirk will not run to fix it.

Does the quirk need to run unconditionally on resume instead of being tied
to the core's power management logic?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260930-b4-elan2514-irq-route-v1-1-44671bf01d05@gmail.com?part=1