Re: [PATCH v2] input: qt602240 - Add ATMEL QT602240 touchscreen driver

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

On 6/28/2010 6:17 PM, Henrik Rydberg wrote:
> Joonyoung Shim wrote:
>> On 6/28/2010 5:34 PM, Henrik Rydberg wrote:
>>> Joonyoung Shim wrote:
>>> [...]
>>>> I see, but i have something wondering at your document.
>>>>
>>>> This is your patch of "Document the MT event slot protocol"
>>>>
>>>> +Protocol Example A
>>>> +------------------
>>>> +
>>>> +Here is what a minimal event sequence for a two-contact touch would look
>>>> +like for a type A device:
>>>> +
>>>> +   ABS_MT_POSITION_X x[0]
>>>> +   ABS_MT_POSITION_Y y[0]
>>>> +   SYN_MT_REPORT
>>>> +   ABS_MT_POSITION_X x[1]
>>>> +   ABS_MT_POSITION_Y y[1]
>>>> +   SYN_MT_REPORT
>>>> +   SYN_REPORT
>>>>
>>>> +The sequence after moving one of the contacts looks exactly the same; the
>>>> +raw data for all present contacts are sent between every synchronization
>>>> +with SYN_REPORT.
>>>>
>>>> -Usage
>>>> ------
>>>> +Here is the sequence after lifting the first contact:
>>>> +
>>>> +   ABS_MT_POSITION_X x[1]
>>>> +   ABS_MT_POSITION_Y y[1]
>>>> +   SYN_MT_REPORT
>>>> +   SYN_REPORT
>>>> +
>>>> +And here is the sequence after lifting the second contact:
>>>> +
>>>> +   SYN_MT_REPORT
>>>> +   SYN_REPORT
>>>> +
>>>>
>>>> Here, there is no reporting for ABS_MT_POSITION_X/Y event, because that
>>>> is the last contact?
>>>> Then, the coordinates of the first contact are x[1] and y[1], right? If 
>>>> yes, it is some confusing, i think they are x[0] and y[0].
>>> It is a bit confusing I agree, but the document is correct. The empty
>>> input_mt_sync() is used when there is no data to report, no lifted fingers,
>>> nothing. Just imagine a device which gets polled periodically.
>>>
>> The thing i wondering is why reports x[1] and y[1] instead of x[0] and 
>> y[0] after lifting the first contact. I have understood the first 
>> contact are x[0] and y[0] and the second contact are x[1] and y[1].
> 
> Yes, after lifting the first contact, what remains is the second contact, which
> is the one getting reported. Again, stateless protocol. ;-)
> 

Do you mean to report the coordinates of contact __remaining__? You told 
me at first, "The position should be the position where the finger left
the surface", so i am confusing.