linux-kernel - Re: [PATCH 3/6] Input: elantech - packet checking for v2 hardware

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Date:	Fri, 19 Aug 2011 14:22:46 +0200
From:	Éric Piel <E.A.B.Piel@...elft.nl>
To:	JJ Ding <jj_ding@....com.tw>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	Seth Forshee <seth.forshee@...onical.com>,
	Aaron Huang <aaron_huang@....com.tw>,
	Tom Lin <tom_lin@....com.tw>,
	Daniel Kurtz <djkurtz@...omium.org>,
	Chase Douglas <chase.douglas@...onical.com>,
	Henrik Rydberg <rydberg@...omail.se>,
	Alessandro Rubini <rubini@...l.unipv.it>
Subject: Re: [PATCH 3/6] Input: elantech - packet checking for v2 hardware

Op 18-08-11 03:57, JJ Ding schreef:
> For v2 hardware, there is no real parity check, but we can still check
> some constant bits for data integrity.
>
> Signed-off-by: JJ Ding<jj_ding@....com.tw>
If you add some comments, as suggest by Dmitry, it looks perfect :-)

Signed-off-by: Éric Piel <eric.piel@...mplin-utc.net>

Éric

> ---
>   drivers/input/mouse/elantech.c |   26 +++++++++++++++++++++++---
>   1 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
> index cf41f23..032181c 100644
> --- a/drivers/input/mouse/elantech.c
> +++ b/drivers/input/mouse/elantech.c
> @@ -376,6 +376,25 @@ static int elantech_check_parity_v1(struct psmouse *psmouse)
>   	       etd->parity[packet[3]] == p3;
>   }
>
> +static int packet_simple_check_v2(struct psmouse *psmouse)
> +{
> +	struct elantech_data *etd = psmouse->private;
> +	unsigned char *packet = psmouse->packet;
> +
> +	if (etd->reports_pressure)
> +		return (packet[0]&  0x0c) == 0x04&&
> +		       (packet[3]&  0x0f) == 0x02;
> +
> +	if ((packet[0]&  0xc0) == 0x80)
> +		return (packet[0]&  0x0c) == 0x0c&&
> +		       (packet[3]&  0x0e) == 0x08;
> +
> +	return (packet[0]&  0x3c) == 0x3c&&
> +	       (packet[1]&  0xf0) == 0x00&&
> +	       (packet[3]&  0x3e) == 0x38&&
> +	       (packet[4]&  0xf0) == 0x00;
> +}
> +
>   /*
>    * Process byte stream from mouse and handle complete packets
>    */
> @@ -398,7 +417,9 @@ static psmouse_ret_t elantech_process_byte(struct psmouse *psmouse)
>   		break;
>
>   	case 2:
> -		/* We don't know how to check parity in protocol v2 */
> +		if (etd->paritycheck&&  !packet_simple_check_v2(psmouse))
> +			return PSMOUSE_BAD_DATA;
> +
>   		elantech_report_absolute_v2(psmouse);
>   		break;
>   	}
> @@ -799,8 +820,7 @@ int elantech_init(struct psmouse *psmouse)
>   		etd->hw_version = 2;
>   		/* For now show extra debug information */
>   		etd->debug = 1;
> -		/* Don't know how to do parity checking for version 2 */
> -		etd->paritycheck = 0;
> +		etd->paritycheck = 1;
>
>   		if (etd->fw_version>= 0x020800)
>   			etd->reports_pressure = true;

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