linux-kernel - Re: [PATCH v3 10/13] HID: hid-multitouch: fix Win 8 protocol

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Date:	Tue, 13 Nov 2012 17:31:38 +0100
From:	"Henrik Rydberg" <rydberg@...omail.se>
To:	Benjamin Tissoires <benjamin.tissoires@...il.com>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Stephane Chatty <chatty@...c.fr>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 10/13] HID: hid-multitouch: fix Win 8 protocol

Hi Benjamin,

> Win 8 specification is much more precise than the Win 7 one.
> Moreover devices that need to take certification must be submitted
> to Microsoft.
> 
> The result is a better protocol support and we can rely on that to
> skip all the messy tests we used to do.
> 

You could possibly start the commit message here..

> The protocol specify the fact that each valid touch must be reported

The win8 protocol...

> within a frame until it is released.
> So we can use the always_valid quirk and dismiss reports when we see

We can therefore...

> duplicates contact ID.

duplicate contacts.

> 
> We recognize Win8 certified devices from their vendor feature 0xff0000c5
> where Microsoft put a signed blob in the report to check if the device
> passed the certification.
> 
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
> ---
>  drivers/hid/hid-multitouch.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> index 351c814..b393c6c 100644
> --- a/drivers/hid/hid-multitouch.c
> +++ b/drivers/hid/hid-multitouch.c
> @@ -53,6 +53,7 @@ MODULE_LICENSE("GPL");
>  #define MT_QUIRK_SLOT_IS_CONTACTID_MINUS_ONE	(1 << 8)
>  #define MT_QUIRK_NO_AREA		(1 << 9)
>  #define MT_QUIRK_IGNORE_DUPLICATES	(1 << 10)
> +#define MT_QUIRK_WIN_8_CERTIFIED	(1 << 11)
>  
>  struct mt_slot {
>  	__s32 x, y, cx, cy, p, w, h;
> @@ -293,6 +294,10 @@ static void mt_feature_mapping(struct hid_device *hdev,
>  			td->maxcontacts = td->mtclass.maxcontacts;
>  
>  		break;
> +	case 0xff0000c5:
> +		if (field->report_count == 256 && field->report_size == 8)
> +			td->mtclass.quirks |= MT_QUIRK_WIN_8_CERTIFIED;
> +		break;
>  	}
>  }
>  
> @@ -679,14 +684,17 @@ static void mt_post_parse_default_settings(struct mt_device *td)
>  {
>  	__s32 quirks = td->mtclass.quirks;
>  
> -	/* unknown serial device needs special quirks */
> -	if (td->touches_by_report == 1) {
> +	/* unknown serial devices or win8 ones need special quirks */
> +	if (td->touches_by_report == 1 || (quirks & MT_QUIRK_WIN_8_CERTIFIED)) {
>  		quirks |= MT_QUIRK_ALWAYS_VALID;
>  		quirks &= ~MT_QUIRK_NOT_SEEN_MEANS_UP;
>  		quirks &= ~MT_QUIRK_VALID_IS_INRANGE;

Won't this line interfere with the hovering functionality?

>  		quirks &= ~MT_QUIRK_VALID_IS_CONFIDENCE;
>  	}
>  
> +	if (quirks & MT_QUIRK_WIN_8_CERTIFIED)
> +		quirks |= MT_QUIRK_IGNORE_DUPLICATES;
> +
>  	td->mtclass.quirks = quirks;
>  }
>  
> -- 
> 1.7.11.7
> 

Thanks,
Henrik
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