Re: [PATCH v2 2/2] HID: sony: Add output events for the multi-touch pad on the Dualshock 4.

[Frank Praznik <frank.praznik@gmail.com>]

On 1/27/2014 15:40, simon@mungewell.org wrote:
>> +	for (n = 0; n < 2; n++) {
>> +		__u16 x, y;
>> +
>> +		x = rd[offset+1] | ((rd[offset+2] & 0xF) << 8);
>> +		y = ((rd[offset+2] & 0xF0) >> 4) | (rd[offset+3] << 4);
>> +
>> +		input_mt_slot(input_dev, n);
>> +		input_mt_report_slot_state(input_dev, MT_TOOL_FINGER,
>> +					!(rd[offset] >> 7));
>> +		input_report_abs(input_dev, ABS_MT_POSITION_X, x);
>> +		input_report_abs(input_dev, ABS_MT_POSITION_Y, y);
>> +
>> +		offset += 4;
>> +	}
> Sorry I have another point/question....
>
> Doesn't this 'spam' the Multitouch interface every incoming report,
> regardless on whether anything has actually change? ie. Should HID-Sony
> track the values, and only send when it detects a change...
>
> Simon
>
No, the HID layer tracks the current state and only sends events when 
something changes so there is no need to shadow it again.  If you watch 
the output in evtest, events are only sent when something changes.  All 
this does is manually parse the touch data for the HID layer.