linux-kernel - Re: [PATCH HID v2 08/11] HID: add per device quirk to force bind to hid-generic

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Message-ID: <20240912061325.GA558003@quokka>
Date: Thu, 12 Sep 2024 16:13:25 +1000
From: Peter Hutterer <peter.hutterer@...-t.net>
To: Benjamin Tissoires <bentiss@...nel.org>
Cc: Jiri Kosina <jikos@...nel.org>, Vicki Pfau <vi@...rift.com>,
	Shuah Khan <shuah@...nel.org>, linux-input@...r.kernel.org,
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org
Subject: Re: [PATCH HID v2 08/11] HID: add per device quirk to force bind to
 hid-generic

On Tue, Sep 10, 2024 at 11:43:44PM +0900, Benjamin Tissoires wrote:
> We already have the possibility to force not binding to hid-generic and
> rely on a dedicated driver, but we couldn't do the other way around.
> 
> This is useful for BPF programs where we are fixing the report descriptor
> and the events, but want to avoid a specialized driver to come after BPF
> which would unwind everything that is done there.
> 
> Signed-off-by: Benjamin Tissoires <bentiss@...nel.org>
> 
> ---
> 
> changes in v2:
> - rely on hdev->quirks for that instead of a new struct for hid_driver

I like this one a lot more than the previous approach, series is 

Reviewed-by: Peter Hutterer <peter.hutterer@...-t.net>

although for 01 and 06 this should be taken with a grain of salt :)

Cheers,
  Peter

> ---
>  drivers/hid/hid-core.c    | 5 +++--
>  drivers/hid/hid-generic.c | 3 +++
>  include/linux/hid.h       | 2 ++
>  3 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index 37e52759a931..bf63e2819baf 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2665,9 +2665,10 @@ static bool hid_check_device_match(struct hid_device *hdev,
>  	/*
>  	 * hid-generic implements .match(), so we must be dealing with a
>  	 * different HID driver here, and can simply check if
> -	 * hid_ignore_special_drivers is set or not.
> +	 * hid_ignore_special_drivers or HID_QUIRK_IGNORE_SPECIAL_DRIVER
> +	 * are set or not.
>  	 */
> -	return !hid_ignore_special_drivers;
> +	return !hid_ignore_special_drivers && !(hdev->quirks & HID_QUIRK_IGNORE_SPECIAL_DRIVER);
>  }
>  
>  static int __hid_device_probe(struct hid_device *hdev, struct hid_driver *hdrv)
> diff --git a/drivers/hid/hid-generic.c b/drivers/hid/hid-generic.c
> index f9db991d3c5a..88882c1bfffe 100644
> --- a/drivers/hid/hid-generic.c
> +++ b/drivers/hid/hid-generic.c
> @@ -40,6 +40,9 @@ static bool hid_generic_match(struct hid_device *hdev,
>  	if (ignore_special_driver)
>  		return true;
>  
> +	if (hdev->quirks & HID_QUIRK_IGNORE_SPECIAL_DRIVER)
> +		return true;
> +
>  	if (hdev->quirks & HID_QUIRK_HAVE_SPECIAL_DRIVER)
>  		return false;
>  
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index d41fa18f1e03..b3a9586363c9 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -359,6 +359,7 @@ struct hid_item {
>   * | @HID_QUIRK_NO_OUTPUT_REPORTS_ON_INTR_EP:
>   * | @HID_QUIRK_HAVE_SPECIAL_DRIVER:
>   * | @HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE:
> + * | @HID_QUIRK_IGNORE_SPECIAL_DRIVER
>   * | @HID_QUIRK_FULLSPEED_INTERVAL:
>   * | @HID_QUIRK_NO_INIT_REPORTS:
>   * | @HID_QUIRK_NO_IGNORE:
> @@ -384,6 +385,7 @@ struct hid_item {
>  #define HID_QUIRK_HAVE_SPECIAL_DRIVER		BIT(19)
>  #define HID_QUIRK_INCREMENT_USAGE_ON_DUPLICATE	BIT(20)
>  #define HID_QUIRK_NOINVERT			BIT(21)
> +#define HID_QUIRK_IGNORE_SPECIAL_DRIVER		BIT(22)
>  #define HID_QUIRK_FULLSPEED_INTERVAL		BIT(28)
>  #define HID_QUIRK_NO_INIT_REPORTS		BIT(29)
>  #define HID_QUIRK_NO_IGNORE			BIT(30)
> 
> -- 
> 2.46.0
>