Re: [PATCH v2 3/3] HID: i2c-hid-of: Fall back to ACPI _DSM when hid-descr-addr is missing

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] The i2c-hid-of driver uses the ACPI _DSM fallback to obtain the HID descriptor address but does not provide a restore_sequence callback to re-evaluate the _DSM during hibernation (S4) restore.
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commit 3ebee1e22f96c1e99e3c6adbd49d92242f2497f9
Author: 谢致邦 (XIE Zhibang) <Yeking@Red54.com>

HID: i2c-hid-of: Fall back to ACPI _DSM when hid-descr-addr is missing

This commit updates the i2c-hid-of driver to fall back to the ACPI _DSM
method for obtaining the HID descriptor address when the "hid-descr-addr"
property is missing. It specifically targets devices using the "PRP0001"
_HID with a "hid-over-i2c" compatible string. Safe default power and reset
delays are also configured for these devices.

> diff --git a/drivers/hid/i2c-hid/i2c-hid-of.c b/drivers/hid/i2c-hid/i2c-hid-of.c
> index 57379b77e9778..e925e2d2cfe0d 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-of.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-of.c
> @@ -92,6 +92,36 @@ static int i2c_hid_of_probe(struct i2c_client *client)
>  	ihid_of->ops.power_down = i2c_hid_of_power_down;
>  
>  	ret = device_property_read_u32(dev, "hid-descr-addr", &val);
> +	if (ret) {
> +		/*
> +		 * Some devices, for example the Lenovo KaiTian N60d and Inspur
> +		 * CP300L3, declare their I2C HID touchpad with _HID "PRP0001"
> +		 * and _DSD compatible "hid-over-i2c" but lack the
> +		 * "hid-descr-addr" property. Fall back to _DSM to obtain the
> +		 * HID descriptor address.
> +		 */
> +		int dsm_ret = i2c_hid_core_acpi_get_descriptor(dev);

[Severity: High]
Does this missing PM callback break S4 hibernation restore?

The native i2c-hid-acpi driver re-evaluates the _DSM method during hibernation
restore via its restore_sequence callback to reinitialize the hardware state,
such as switching the hardware back from PS/2 emulation to I2C-HID mode.

Because this ACPI _DSM fallback is added in i2c_hid_of_probe() without also
wiring up ops.restore_sequence in the OF driver, will these touchpads fail
to resume correctly and become unresponsive after waking from S4?

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Sashiko AI review · https://sashiko.dev/#/patchset/20260601181510.38705-1-Yeking@Red54.com?part=3