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

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

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].

> [...]
>>> I see. And you want BTN_TOUCH to follow the logic for the single touch? I think
>>> that is the main issue here. We can have _one_ of the following definitions, but
>>> not both:
>>>
>>> 1. input_report_key(input_dev, BTN_TOUCH, finger_num > 0);
>>>
>> OK, i will use this. This was original code.
>>
>>> 2. input_report_key(input_dev, BTN_TOUCH,
>>>                     finger[single_id].status != QT602240_RELEASE);
>>>
>>> If you use the latter, there should be another event to denote the finger_num ==
>>> 0 case. This line at the end should do it:
>>>
>>> if (finger_num == 0)
>>> 	input_mt_sync(input_dev);
>>>
>> I don't know why this needs?
> 
> The general reason is the one given above. Since you are going with the first
> option, it won't be needed.
> 

But, input_mt_sync is reported already with reporting of ABS_MT_POSITION_X/Y.
I meant the case of single touch reporting.