Re: [PATCH v4 01/11] HID: asus: refactor init sequence per spec

["Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>]

On Mon, 24 Mar 2025, Antheas Kapenekakis wrote:

> Currently, asus_kbd_init() uses a reverse engineered init sequence
> from Windows, which contains the handshakes from multiple programs.
> Keep the main one, which is 0x5a (meant for brightness drivers).
> 
> In addition, perform a get_response and check if the response is the
> same. To avoid regressions, print an error if the response does not
> match instead of rejecting device.
> 
> Then, refactor asus_kbd_get_functions() to use the same ID it is called
> with, instead of hardcoding it to 0x5a so that it may be used for 0x0d
> in the future.
> 
> Signed-off-by: Antheas Kapenekakis <lkml@antheas.dev>
> ---
>  drivers/hid/hid-asus.c | 82 +++++++++++++++++++++++-------------------
>  1 file changed, 46 insertions(+), 36 deletions(-)
> 
> diff --git a/drivers/hid/hid-asus.c b/drivers/hid/hid-asus.c
> index 46e3e42f9eb5f..8d4df1b6f143b 100644
> --- a/drivers/hid/hid-asus.c
> +++ b/drivers/hid/hid-asus.c
> @@ -48,7 +48,7 @@ MODULE_DESCRIPTION("Asus HID Keyboard and TouchPad");
>  #define FEATURE_REPORT_ID 0x0d
>  #define INPUT_REPORT_ID 0x5d
>  #define FEATURE_KBD_REPORT_ID 0x5a
> -#define FEATURE_KBD_REPORT_SIZE 16
> +#define FEATURE_KBD_REPORT_SIZE 64
>  #define FEATURE_KBD_LED_REPORT_ID1 0x5d
>  #define FEATURE_KBD_LED_REPORT_ID2 0x5e
>  
> @@ -388,14 +388,41 @@ static int asus_kbd_set_report(struct hid_device *hdev, const u8 *buf, size_t bu
>  
>  static int asus_kbd_init(struct hid_device *hdev, u8 report_id)
>  {
> -	const u8 buf[] = { report_id, 0x41, 0x53, 0x55, 0x53, 0x20, 0x54,
> -		     0x65, 0x63, 0x68, 0x2e, 0x49, 0x6e, 0x63, 0x2e, 0x00 };
> +	/*
> +	 * Asus handshake identifying us as a driver (0x5A)
> +	 * 0x5A then ASCII for "ASUS Tech.Inc."
> +	 * 0x5D is for userspace Windows applications.
> +	 *
> +	 * The handshake is first sent as a set_report, then retrieved
> +	 * from a get_report to verify the response.
> +	 */
> +	const u8 buf[] = { report_id, 0x41, 0x53, 0x55, 0x53, 0x20,
> +		0x54, 0x65, 0x63, 0x68, 0x2e, 0x49, 0x6e, 0x63, 0x2e, 0x00 };
> +	u8 *readbuf;
>  	int ret;
>  
>  	ret = asus_kbd_set_report(hdev, buf, sizeof(buf));
> -	if (ret < 0)
> -		hid_err(hdev, "Asus failed to send init command: %d\n", ret);
> +	if (ret < 0) {
> +		hid_err(hdev, "Asus failed to send handshake: %d\n", ret);
> +		return ret;
> +	}
>  
> +	readbuf = kzalloc(FEATURE_KBD_REPORT_SIZE, GFP_KERNEL);
> +	if (!readbuf)
> +		return -ENOMEM;
> +
> +	ret = hid_hw_raw_request(hdev, report_id, readbuf,
> +				 FEATURE_KBD_REPORT_SIZE, HID_FEATURE_REPORT,
> +				 HID_REQ_GET_REPORT);
> +	if (ret < 0) {
> +		hid_err(hdev, "Asus failed to receive handshake ack: %d\n", ret);
> +	} else if (memcmp(readbuf, buf, sizeof(buf)) != 0) {
> +		hid_err(hdev, "Asus handshake returned invalid response: %*ph\n",
> +			FEATURE_KBD_REPORT_SIZE, readbuf);
> +		// Do not return error if handshake is wrong to avoid regressions

Should it be on warn/info level if the error is ignored.

> +	}
> +
> +	kfree(readbuf);
>  	return ret;
>  }
>  
> @@ -417,7 +444,7 @@ static int asus_kbd_get_functions(struct hid_device *hdev,
>  	if (!readbuf)
>  		return -ENOMEM;
>  
> -	ret = hid_hw_raw_request(hdev, FEATURE_KBD_REPORT_ID, readbuf,
> +	ret = hid_hw_raw_request(hdev, report_id, readbuf,
>  				 FEATURE_KBD_REPORT_SIZE, HID_FEATURE_REPORT,
>  				 HID_REQ_GET_REPORT);
>  	if (ret < 0) {
> @@ -540,42 +567,25 @@ static int asus_kbd_register_leds(struct hid_device *hdev)
>  	unsigned char kbd_func;
>  	int ret;
>  
> -	if (drvdata->quirks & QUIRK_ROG_NKEY_KEYBOARD) {
> -		/* Initialize keyboard */
> -		ret = asus_kbd_init(hdev, FEATURE_KBD_REPORT_ID);
> -		if (ret < 0)
> -			return ret;
> -
> -		/* The LED endpoint is initialised in two HID */
> -		ret = asus_kbd_init(hdev, FEATURE_KBD_LED_REPORT_ID1);
> -		if (ret < 0)
> -			return ret;
> -
> -		ret = asus_kbd_init(hdev, FEATURE_KBD_LED_REPORT_ID2);
> -		if (ret < 0)
> -			return ret;
> +	ret = asus_kbd_init(hdev, FEATURE_KBD_REPORT_ID);
> +	if (ret < 0)
> +		return ret;
>  
> -		if (dmi_match(DMI_PRODUCT_FAMILY, "ProArt P16")) {
> -			ret = asus_kbd_disable_oobe(hdev);
> -			if (ret < 0)
> -				return ret;
> -		}
> -	} else {
> -		/* Initialize keyboard */
> -		ret = asus_kbd_init(hdev, FEATURE_KBD_REPORT_ID);
> -		if (ret < 0)
> -			return ret;
> +	/* Get keyboard functions */
> +	ret = asus_kbd_get_functions(hdev, &kbd_func, FEATURE_KBD_REPORT_ID);
> +	if (ret < 0)
> +		return ret;
>  
> -		/* Get keyboard functions */
> -		ret = asus_kbd_get_functions(hdev, &kbd_func, FEATURE_KBD_REPORT_ID);
> +	if (dmi_match(DMI_PRODUCT_FAMILY, "ProArt P16")) {
> +		ret = asus_kbd_disable_oobe(hdev);
>  		if (ret < 0)
>  			return ret;
> -
> -		/* Check for backlight support */
> -		if (!(kbd_func & SUPPORT_KBD_BACKLIGHT))
> -			return -ENODEV;
>  	}
>  
> +	/* Check for backlight support */
> +	if (!(kbd_func & SUPPORT_KBD_BACKLIGHT))
> +		return -ENODEV;
> +
>  	drvdata->kbd_backlight = devm_kzalloc(&hdev->dev,
>  					      sizeof(struct asus_kbd_leds),
>  					      GFP_KERNEL);
> 

-- 
 i.