[Gta04-owner] Using touchscreen as a touchpad?

Neil Jerram neil at ossau.homelinux.net
Fri Apr 22 13:00:10 CEST 2016


On 21/04/16 20:04, Neil Jerram wrote:
> On 21/04/16 13:08, Neil Jerram wrote:
>> Has anyone tried configuring the GTA04 touchscreen to behave as a
>> touchpad instead of a touchscreen?  Would the kernel code for the
>> touchscreen support that?
>>
>> Subject to the latter, I think the former is possible in principle by
>> using libinput and configuring a udev rule like this:
>>
>> ACTION=="add|change", KERNEL=="event[0-9]*", ENV{ID_VENDOR_ID}=="...",
>> ENV{ID_MODEL_ID}=="...b", ENV{ID_INPUT_TOUCHSCREEN}="",
>> ENV{ID_INPUT_TOUCHPAD}="1"
>
> Well, unfortunately it does not work.  Xorg.0.log says:
>
> [    19.473] (II) input device 'TSC2007 Touchscreen', 
> /dev/input/event0 is tagged by udev as: Touchpad Touchscreen
> [    19.473] (EE) kernel bug: device TSC2007 Touchscreen failed 
> touchpad sanity checks
> [    19.473] (II) input device 'TSC2007 Touchscreen', 
> /dev/input/event0 is a touchpad
> [    19.540] (II) failed to create input device '/dev/input/event0'.
>
> I guess libinput is expecting some minimal characteristics for a 
> 'touchpad', and the TSC2007 kernel driver doesn't provide those. Pity, 
> because I would like to see if it was usable that way.

Yes, libinput checks for ABS_X, BTN_TOUCH and BTN_TOOL_FINGER.  The 
driver provides ABS_X and BTN_TOUCH but not BTN_TOOL_FINGER.

It looks like a trivial change to get the driver to advertise 
BTN_TOOL_FINGER, so I plan to try that next.  If it works we could 
implement a driver option for it, so as to allow either touchscreen or 
touchpad use.

Regards,
     Neil



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