Re: [PATCH] input : wacom - report resolution for ABS_MT events

[Ping Cheng <pinglinux@gmail.com>]

On Fri, Jan 28, 2011 at 11:12 AM, Henrik Rydberg <rydberg@euromail.se> wrote:
>> >> This is mainly required by the serial pen and touch devices since
>> >> both pen and touch are on the same port. Updated the USB ones to
>> >> keep MT event definition consistent among serial and USB devices.
>> >
>> > Why is this change performed? What does the patch do? Please elaborate
>> > a little bit.
>>
>> Let's see if I can explain it clearer or not.
>>
>> We need to report resolution to userland for wacom_w8001.c.
>
> Thanks, perfect - sentences like this one is great to put in the patch
> description.

Thanks for the encouragement ;).

>> Since pen
>> and touch data are reported through the same logical port for serial
>> devices, using input_abs_set_res  for ABS_X/Y,  we can only pass the
>> resolution for pen or touch. So, I let ABS_X/Y report pen resolution
>> since most legacy ST clients process pen data over touch. However, for
>> multi-touch clients, especially for those that support gestures, touch
>> resolution is needed to calculate the physical distance between two
>> touch points. Using  ABS_MT_POSITION_X/Y does not cause confusion and
>> it is quite intuitive.
>
> I thought this was solved by reporting both pen and touch on the same
> scale, which would render this problem moot. Or?

Yeah, see my reply to Dmitry for detail.

> [...]
>> > Is this for the BAMBOO_PT case? What about the extra x/y scaling for
>> > some of those devices?
>>
>> Yes, it is for Bamboo. We do not need to scale the value here since
>> touch and pen are on different ports. We had to scale the value for
>> wacom_w8001 since both pen and touch are on the same port. Without
>> scaling the data, the pen/finger tip will not follow the cursor on the
>> screen (wacom_w8001 is a touchscren device).
>
> I was thinking of the scaling quirk in effect for the Bamboo
> Touch. The resolution would have to change as well.

Yes, If we need to report the right values ;).

Ping
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