linux-kernel - Re: [PATCH 14/22 v4] Input: atmel_mxt_ts - don't re-read matrix after applying pdata

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Date:	Mon, 18 Jun 2012 15:50:01 -0400
From:	Yufeng Shen <miletus@...gle.com>
To:	Nick Dyer <nick.dyer@...ev.co.uk>
Cc:	Daniel Kurtz <djkurtz@...omium.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Henrik Rydberg <rydberg@...omail.se>,
	Joonyoung Shim <jy0922.shim@...sung.com>,
	linux-input@...r.kernel.org,
	Iiro Valkonen <iiro.valkonen@...el.com>,
	Benson Leung <bleung@...omium.org>,
	Olof Johansson <olofj@...omium.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/22 v4] Input: atmel_mxt_ts - don't re-read matrix after
 applying pdata

On Mon, Jun 18, 2012 at 11:03 AM, Nick Dyer <nick.dyer@...ev.co.uk> wrote:
> Daniel Kurtz wrote:
>> The matrix x/y size in the Info ID Block represents the number of x/y
>> trace lines on the device.  There is no need to re-read them after
>> applying pdata config, since pdata only configures the object table
>> etnries.  The matrix size read from the ID can only be updated by a
>> firmware update.
>
> This isn't correct. For example, mXT224 can be configured as 16x14, 17x13,
> 18x12, etc. This only takes effect when the chip is reset, which is why it
> is necessary to re-read them after applying the config.
>

so look at structure mxt_info

 struct mxt_info {
          u8 family_id;
          u8 variant_id;
          u8 version;
          u8 build;
          u8 matrix_xsize;
          u8 matrix_ysize;
          u8 object_num;
};

I think it is meant to be corresponding to Information Block of the
device, of which
the matrix_xsize and matrix_ysize mean "The size of the matrix the
device supports",
which should be fixed for a certain chip.

The configurable matrix size is in T9 XSIZE/YSIZE, which, if ever
needed to be read back,
probably read back into something other than mxt_info struct.


> cheers
>
> --
> Nick Dyer
> Software Engineer, ITDev Ltd
> Hardware and Software Development Consultancy
> Website: http://www.itdev.co.uk
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