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

On Tue, Jun 19, 2012 at 6:26 AM, Nick Dyer [off-list ref] wrote:

Yufeng Shen wrote:

quoted

On Mon, Jun 18, 2012 at 11:03 AM, Nick Dyer [off-list ref] wrote:

quoted

Daniel Kurtz wrote:

quoted

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.

As I said, it's not fixed, there is a mode setting (T28 byte 2) which
alters the matrix size. This is documented in the protocol guide, if you
have it.

You can also verify this if you want: change mode setting, backup, reset,
and read the information block, you'll see the matrix size changes. I've
just checked that myself on an mXT224.

Ah, you are correct. I was looking at the wrong protocol guide. mXT224(E) does
have the mode setting option.

I also asked the guys at Atmel that I work with, and they confirm that this
behaviour is as designed.

quoted

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.

The position of the touchscreen within the matrix is a separate
configurable setting, you're confusing the two.

cheers

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

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