[RFC XI 2.1 - xf86-input-evdev 2/3] Add experimental XI 2.1 multitouch support

Ping Cheng pinglinux at gmail.com
Mon Dec 6 12:17:19 PST 2010

On Mon, Dec 6, 2010 at 9:41 AM, Chase Douglas
<chase.douglas at canonical.com> wrote:
> On 12/05/2010 10:41 PM, Peter Hutterer wrote:
>> if the kernel can send it through one device, we can handle it, right?
>> if both are sent through the same axes (and need a serial or something to
>> differentiate like the wacom drivers) then yes, they need to be split up
>> into multiple devices.
> I think we're in agreement about what we can handle. We should be able
> to handle whatever the kernel sends us. But I feel that it's impossible
> to have a kernel device that sends touch information through the same
> properties for different surfaces. Thus, we don't need per-axis touch modes.
> To push towards a resolution to this issue, Peter, Ping, do you still
> feel we will need per-axis touch modes? If you do, then I could use more
> detail on how such a device would be defined through the evdev or touch
> class interface. Maybe I'm missing something obvious?

I don't know. Since the issue that xf86-input-wacom encountered has
been fixed in 1.9 (as Peter said), we don't need per-axis mode for the
current implementation. But, if we want to attach the touch strips to
a tool on the tablet (it can be fingers), all axes of the same too are
in the same mode could be an issue.

Take touchpad for example. Finger as a tool will be in relative mode
since we need to post (x,y) movement in relative mode. But raw strip
data need to be posted in absolute mode.

I don't have a certain opinion on this since I am not familiar with
XInput and xf86-input-evdev code. Peter has involved in all three
development. I'll go with his decision.


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