evdev: eGalax Touchscreen.

[Peter Hutterer]

On Tue, May 12, 2009 at 11:13:56PM -0400, Pat Suwalski wrote:
> I have a few pieces of eGalax touchscreen hardware that seem to behave
> differently with evdev.
> 
> First off, I noticed that calibration using the latest xinput tool
> (1.4.1) doesn't work (this is X 1.6.1 with evdev 2.2.2 and today's git).
> 
> Should a touchpad respect the calibrations set by xinput? Looking for
> calibration in evdev.c only shows it being used in the Wacom-ish section.
> 
> Secondly, the other touchscreen doesn't work at all. After fiddling
> around for a while, it appears that the coordinates are supplied in
> pEvdev->vals[] 2,3 rather than 0,1. Adding code in the EV_ABS case
> (~line 400) like so:
> 
>    if (ev->code == 2)
>      ev->code = ABS_X;
>    if (ev->code == 3)
>      ev->code = ABS_Y;
> 
> makes events click into place and work like the first touchscreen.
> 
> This output suggests that it's treated as a touchpad rather than a
> touchscreen:
> 
> (**) eGalax Inc. USB TouchController: always reports core events
> (**) eGalax Inc. USB TouchController: Device: "/dev/input/event8"
> (II) eGalax Inc. USB TouchController: Found 2 mouse buttons
> (II) eGalax Inc. USB TouchController: found absolute axes
> (II) eGalax Inc. USB TouchController: Found x and y absolute axes
> (II) eGalax Inc. USB TouchController: Found absolute touchpad
> (II) eGalax Inc. USB TouchController: Configuring as touchpad
> (**) eGalax Inc. USB TouchController: YAxisMapping: buttons 4 and 5
> (**) eGalax Inc. USB TouchController: EmulateWheelButton: 4,
> EmulateWheelInertia: 10, EmulateWheelTimeout: 200
> (II) XINPUT: Adding extended input device "eGalax Inc. USB
> TouchController" (type: TOUCHPAD)
> 
> The reason for this is that num_buttons is 3. Upon investigating
> further, they are BTN_LEFT, BTN_RIGHT, and BTN_MIDDLE. I suspect it
> might have something to do with the following in the usbtouchscreen.c
> from the kernel:
> 
>          /* ignore the HID capable devices, handled by usbhid */
>          {USB_DEVICE_HID_CLASS(0x0eef, 0x0001), .driver_info =
> DEVTYPE_IGNORE},
>          {USB_DEVICE_HID_CLASS(0x0eef, 0x0002), .driver_info =
> DEVTYPE_IGNORE},
> 
> Possibly, if they are treating this device as plain HID, it
> automatically gains buttons? The USB ID on both parts (which are
> different) is 0x0eef:0x0001.
> 
> Here is the real kicker. If forced to go into the Wacom/calibration
> block by commenting out:
> 
>      abs = 0;
>      rel = 1;
> 
> at least one of the touchscreens is perfectly calibrated. The other no
> longer has funny relative drag events.
> 
> I'm really looking for advice here, as it seems that more than one thing
> is broken or at least contributing to problems. It would be really nice
> to get touchscreens working a little better with evdev, and not have to
> use evtouch. I'm not sure if my problems are related to kernel, X-evdev,
> or something in between.

Pat:
This problem isn't uncommon, I've had my hands on a touchscreen that had
similar issues. Please file a bugreport on bugs.freedesktop.org with this
information and I'll help you then. It's easier to consolidate information
in a bugreport than over a number of emails.

Cheers,
  Peter