[PATCH] HID: i2c-hid-acpi: Add PRP0001 to match table and OF alias

[PATCH] HID: i2c-hid-acpi: Add PRP0001 to match table and OF alias

[谢致邦 (XIE Zhibang)]

Some devices, for example the Lenovo KaiTian N60d and Inspur CP300L3,
declare their I2C HID ACPI touchpad in the DSDT as _HID "PRP0001" with
_DSD compatible "hid-over-i2c" instead of the standard "PNP0C50". This
worked before commit b33752c30023 ("HID: i2c-hid: Reorganize so ACPI and
OF are separate modules"), but after the split, PRP0001 devices on the
ACPI bus are no longer probed by either driver.

Fix this by adding PRP0001 to i2c_hid_acpi_match so the driver probes
these devices. The existing _DSM HID descriptor call in probe()
naturally rejects any PRP0001 device that does not implement the
protocol.

A MODULE_ALIAS is also needed for autoloading: when an ACPI device has a
_DSD "compatible" property, the uevent modalias uses the OF format
(of:N<name>T<compatible>) instead of the ACPI format (acpi:<HID>), so
udev would otherwise load only i2c-hid-of, which fails to probe because
these devices lack the "hid-descr-addr" property.

Fixes: b33752c30023 ("HID: i2c-hid: Reorganize so ACPI and OF are separate modules")
Signed-off-by: 谢致邦 (XIE Zhibang) <Yeking@Red54.com>
---
 drivers/hid/i2c-hid/i2c-hid-acpi.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/hid/i2c-hid/i2c-hid-acpi.c b/drivers/hid/i2c-hid/i2c-hid-acpi.c
index abd700a101f4..515ced22c978 100644
--- a/drivers/hid/i2c-hid/i2c-hid-acpi.c
+++ b/drivers/hid/i2c-hid/i2c-hid-acpi.c
@@ -119,10 +119,30 @@ static int i2c_hid_acpi_probe(struct i2c_client *client)
 static const struct acpi_device_id i2c_hid_acpi_match[] = {
 	{ "ACPI0C50" },
 	{ "PNP0C50" },
+	/*
+	 * Some devices, for example the Lenovo KaiTian N60d and Inspur CP300L3,
+	 * declare their I2C HID ACPI touchpad in the DSDT as _HID "PRP0001"
+	 * with _DSD compatible "hid-over-i2c" instead of the standard
+	 * "PNP0C50". This worked before i2c-hid was split into i2c-hid-acpi
+	 * and i2c-hid-of, but PRP0001 devices on the ACPI bus are no longer
+	 * probed after the split. The _DSM call in probe() naturally rejects
+	 * PRP0001 devices that are not actually I2C HID, so matching PRP0001
+	 * here is safe.
+	 */
+	{ "PRP0001" },
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, i2c_hid_acpi_match);
 
+	/*
+	 * When an ACPI device has a _DSD "compatible" property, the uevent
+	 * modalias uses the OF format (of:N<name>T<compatible>) instead of
+	 * the ACPI format (acpi:<HID>). Add an OF alias so udev can autoload
+	 * this module for such devices. probe() will reject pure DT devices
+	 * via the _DSM HID descriptor call.
+	 */
+MODULE_ALIAS("of:N*TChid-over-i2c");
+
 static struct i2c_driver i2c_hid_acpi_driver = {
 	.driver = {
 		.name	= "i2c_hid_acpi",
-- 
2.43.0

Re: [PATCH] HID: i2c-hid-acpi: Add PRP0001 to match table and OF alias

[Hans de Goede]

Hi,

On 27-May-26 17:17, 谢致邦 (XIE Zhibang) wrote:
> Some devices, for example the Lenovo KaiTian N60d and Inspur CP300L3,
> declare their I2C HID ACPI touchpad in the DSDT as _HID "PRP0001" with
> _DSD compatible "hid-over-i2c" instead of the standard "PNP0C50". This
> worked before commit b33752c30023 ("HID: i2c-hid: Reorganize so ACPI and
> OF are separate modules"), but after the split, PRP0001 devices on the
> ACPI bus are no longer probed by either driver.
> 
> Fix this by adding PRP0001 to i2c_hid_acpi_match so the driver probes
> these devices. The existing _DSM HID descriptor call in probe()
> naturally rejects any PRP0001 device that does not implement the
> protocol.
> 
> A MODULE_ALIAS is also needed for autoloading: when an ACPI device has a
> _DSD "compatible" property, the uevent modalias uses the OF format
> (of:N<name>T<compatible>) instead of the ACPI format (acpi:<HID>), so
> udev would otherwise load only i2c-hid-of, which fails to probe because
> these devices lack the "hid-descr-addr" property.

Ok, so first of all please contact the vendors of these devices to fix
their firmware.

Either a _HID "PRP0001" value should be used with a *full* of description
matching the binding from Documentation/devicetree/bindings/input/hid-over-i2c.yaml
including hid-descr-addr. Or the firmware should use PNP0C50 + the _DSM
method to get the hid-desc-addr. Mixing and matching these 2 is bad,
very very bad.

IMHO the fix here as is is not acceptable this will make the i2c_hid_acpi
module load and worse *probe* every ACPI device with a "PRP0001" HID.

You claim the existing _DSM HID descriptor call will save the driver from
actually doing much of anything but IMHO that should not be relied on.

Currently the i2c_hid_of driver will get automatically loaded + try
to probe the device, but as you say this will fail due to lacking
hid-desc-addr. Have you tried adding DMI quirks to i2c_hid_of to
provide the hid-desc-addr through a quirk?  (I wonder if the IRQ will
get picked up ok)

That seems a better solution than making 2 drivers probe the same
"hid-over-i2c" compatible and let one fail (with an ugly error msg
in the logs), while also making i2c_hid_acpi probe all PRP0001 devices
and make that fail (with more err logging) on all other devices.

I see the 2 laptops here are both using a Loongson architecture,
so any fix for this should IMHO also be wrapped in
#ifdef CONFIG_LOONGARCH ... #endif

Regards,

Hans





> 
> Fixes: b33752c30023 ("HID: i2c-hid: Reorganize so ACPI and OF are separate modules")
> Signed-off-by: 谢致邦 (XIE Zhibang) <Yeking@Red54.com>
> ---
>  drivers/hid/i2c-hid/i2c-hid-acpi.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/hid/i2c-hid/i2c-hid-acpi.c b/drivers/hid/i2c-hid/i2c-hid-acpi.c
> index abd700a101f4..515ced22c978 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-acpi.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-acpi.c
> @@ -119,10 +119,30 @@ static int i2c_hid_acpi_probe(struct i2c_client *client)
>  static const struct acpi_device_id i2c_hid_acpi_match[] = {
>  	{ "ACPI0C50" },
>  	{ "PNP0C50" },
> +	/*
> +	 * Some devices, for example the Lenovo KaiTian N60d and Inspur CP300L3,
> +	 * declare their I2C HID ACPI touchpad in the DSDT as _HID "PRP0001"
> +	 * with _DSD compatible "hid-over-i2c" instead of the standard
> +	 * "PNP0C50". This worked before i2c-hid was split into i2c-hid-acpi
> +	 * and i2c-hid-of, but PRP0001 devices on the ACPI bus are no longer
> +	 * probed after the split. The _DSM call in probe() naturally rejects
> +	 * PRP0001 devices that are not actually I2C HID, so matching PRP0001
> +	 * here is safe.
> +	 */
> +	{ "PRP0001" },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(acpi, i2c_hid_acpi_match);
>  
> +	/*
> +	 * When an ACPI device has a _DSD "compatible" property, the uevent
> +	 * modalias uses the OF format (of:N<name>T<compatible>) instead of
> +	 * the ACPI format (acpi:<HID>). Add an OF alias so udev can autoload
> +	 * this module for such devices. probe() will reject pure DT devices
> +	 * via the _DSM HID descriptor call.
> +	 */
> +MODULE_ALIAS("of:N*TChid-over-i2c");
> +
>  static struct i2c_driver i2c_hid_acpi_driver = {
>  	.driver = {
>  		.name	= "i2c_hid_acpi",

Re: [PATCH] HID: i2c-hid-acpi: Add PRP0001 to match table and OF alias

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Adding `PRP0001` directly to the ACPI match table incorrectly bypasses `compatible` string matching, causing the driver to intercept all PRP0001 I2C devices and spam the kernel log.
--

commit 7d0ee8c935eaadd4f5e66e197d5712a960fd31f5
Author: 谢致邦 (XIE Zhibang) <Yeking@Red54.com>

HID: i2c-hid-acpi: Add PRP0001 to match table and OF alias

This commit adds the PRP0001 ACPI ID to the i2c-hid-acpi driver's match
table and manually defines an OF module alias. This is intended to allow the
driver to probe devices that declare themselves as PRP0001 with a "hid-over-i2c"
compatible string in their _DSD.

> diff --git a/drivers/hid/i2c-hid/i2c-hid-acpi.c b/drivers/hid/i2c-hid/i2c-hid-acpi.c
> index abd700a101f46..515ced22c978d 100644
> --- a/drivers/hid/i2c-hid/i2c-hid-acpi.c
> +++ b/drivers/hid/i2c-hid/i2c-hid-acpi.c
> @@ -119,10 +119,30 @@ static int i2c_hid_acpi_probe(struct i2c_client *client)
>  static const struct acpi_device_id i2c_hid_acpi_match[] = {
>  	{ "ACPI0C50" },
>  	{ "PNP0C50" },
> +	/*
> +	 * Some devices, for example the Lenovo KaiTian N60d and Inspur CP300L3,
> +	 * declare their I2C HID ACPI touchpad in the DSDT as _HID "PRP0001"
> +	 * with _DSD compatible "hid-over-i2c" instead of the standard
> +	 * "PNP0C50". This worked before i2c-hid was split into i2c-hid-acpi
> +	 * and i2c-hid-of, but PRP0001 devices on the ACPI bus are no longer
> +	 * probed after the split. The _DSM call in probe() naturally rejects
> +	 * PRP0001 devices that are not actually I2C HID, so matching PRP0001
> +	 * here is safe.
> +	 */
> +	{ "PRP0001" },

[Severity: Medium]
Does adding PRP0001 directly to the ACPI match table bypass the OF compatible
string check in __acpi_match_device()?

PRP0001 is a special identifier used by the ACPI subsystem to defer matching
to the OF compatible string within the device's _DSD. When PRP0001 is
explicitly added here, the match returns true immediately without checking the
compatible string.

If a system has other unrelated I2C devices using PRP0001 (like temperature
sensors or RTCs utilizing compatible strings), won't the driver core attempt
to bind i2c-hid-acpi to all of them?

Because i2c_hid_acpi_probe() unconditionally evaluates the HID _DSM which will
fail for these unrelated devices, does this introduce boot delays and pollute
the kernel log with false-positive "Error _DSM call to get HID descriptor
address failed" messages for every non-HID PRP0001 device?

>  	{ }
>  };
>  MODULE_DEVICE_TABLE(acpi, i2c_hid_acpi_match);
>  
> +	/*
> +	 * When an ACPI device has a _DSD "compatible" property, the uevent
> +	 * modalias uses the OF format (of:N<name>T<compatible>) instead of
> +	 * the ACPI format (acpi:<HID>). Add an OF alias so udev can autoload
> +	 * this module for such devices. probe() will reject pure DT devices
> +	 * via the _DSM HID descriptor call.
> +	 */
> +MODULE_ALIAS("of:N*TChid-over-i2c");

[Severity: Medium]
Instead of manually defining this MODULE_ALIAS, could we define an
of_device_id match table containing { .compatible = "hid-over-i2c" }?

Using an of_device_id table would naturally solve the matching logic by
allowing the ACPI core to correctly evaluate the _DSD compatible string.
This prevents intercepting unrelated PRP0001 devices, and the driver core
would automatically generate the correct, robust module alias for autoloading.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/tencent_61698D7A14AC9BFE6C9F3FDB797FCA02E309@qq.com?part=1