Re: [PATCH 1/3 v2] Input: atmel_mxt_ts - Make wait-after-reset period compatible with all chips

[Joonyoung Shim <jy0922.shim@samsung.com>]

On 2011-07-05 오후 4:12, Iiro Valkonen wrote:
> Hello,
>
> On 07/05/2011 04:07 AM, Joonyoung Shim wrote:
>> Hi,
>>
>> On 2011-07-04 오후 9:57, Iiro Valkonen wrote:
>>> The delay before the chip can be accessed after reset varies between different
>>> chips in maXTouch family. Waiting for 200ms and then monitoring the CHG (chip
>>> is ready when the line is low) is guaranteed to work with all chips.
>>
>> I wonder 200ms waiting needs indeed, it is very long time.
>> If monitoring the CHG line can detect the completion of reset,
>> 200ms waiting can be removed?
>>

My question is monitoring the CHG line can substitute 
"msleep(MXT_RESET_TIME)"? In other words, i want to remove
msleep(MXT_RESET_TIME) and add only waiting until CHG line is low.

>
> Yes, 200ms is a bit longish. But it is what we need to guarantee correct
> functionality with all chips in all situations. I would prefer to see that
> in the mainline version. Anyone worried about the delay could maybe adjust
> the value to suit his/her needs, for example with mXT224 you could get away with
> using just 65ms, like in the original version. Another option would be to
> check the family ID in the driver, and wait just long enough. Drawback with
> that is that the driver (possibly) needs updating with every new chip. I'd
> like to keep this simple&  robust, wait 200ms which works for every current
> (and most likely with every upcoming) chip, and take the small delay penalty.
>

The 200ms delay is sometimes a problem for fastbooting, and if each
chip has different delay value, i think it's better that driver supports
suitable delay value of the chip because it isn't difficult stuff.
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