Re: [PATCH v3 1/4] HID: generic: Respect specialized drivers match callbacks

[Guenter Roeck]

On 9/14/26 16:37, Vas Zayarskiy wrote:
> A driver can reject an interface in its match callback even when its ID
> table matches. hid-generic currently yields based on the ID table alone,
> leaving such an interface without a driver.
>
> Consult the callback after matching the ID table so hid-generic can keep
> interfaces declined by specialized drivers. This allows the AMPINEL
> hwmon driver to leave the separate keyboard interface to hid-generic.
>
> The same callback check was proposed previously for Logitech devices:
>
> Link: https://lkml.iu.edu/hypermail/linux/kernel/2212.0/06724.html

That was from 2022 and seems to have been abandoned, making me wonder
if it is still broken for Logitech devices or if another solution
was found.

Guenter

> Assisted-by: LLM sparse
> Signed-off-by: Vas Zayarskiy <contact@xxxxxxxxx>
> ---
>   drivers/hid/hid-generic.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hid/hid-generic.c b/drivers/hid/hid-generic.c
> index c2de91674..ebc38ae76 100644
> --- a/drivers/hid/hid-generic.c
> +++ b/drivers/hid/hid-generic.c
> @@ -31,7 +31,13 @@ static int __check_hid_generic(struct device_driver *drv, void *data)
>   	if (hdrv == &hid_generic)
>   		return 0;
>   
> -	return hid_match_device(hdev, hdrv) != NULL;
> +	if (!hid_match_device(hdev, hdrv))
> +		return 0;
> +
> +	if (hdrv->match)
> +		return hdrv->match(hdev, false);
> +
> +	return 1;
>   }
>   
>   static bool hid_generic_match(struct hid_device *hdev,