Hello Donald,

I think that you are encountering at least 3 problems:
1) your devices are not correctly handled by the kernel
2) solving the handling of multitouch devices by adding the quirk
HID_QUIRK_MULTI_INPUT is __really__ a bad idea in your case
3) you seem to use very old kernels.

So:
1) between 2.6.34 and 2.6.39, Mosart devices are handled in
hid-mosart, and since 3.0 through hid-multitouch. Using these drivers
will allow you to have a better support of your devices.
However I'm not 100% sure it won't create more than one input device
if your hardware declares more than one interface.

2) Using the quirk HID_QUIRK_MULTI_INPUT is the exact opposite of what
you want to do -> it creates several inputs when it sees several
touches -> you then have a lot of inputs with unusable stuff.

3) By using a kernel >=3.4 and by modprobing hid-multitouch, your
mosart devices will be correctly handled by the kernel.

However, if you can not update your kernel here are some ideas:
- use the right module for your devices (hid-mosart or hid-multitouch)
- patch your kernel (> 2.6.35) using the patches here:
http://www.lii-enac.fr/en/architecture/linux-input/multitouch-howto.html#get
(but I did not tested old kernel releases) -> you will get the same
input layer for multitouch than a 3.4 kernel (the older the kernel is,
the more intrusive it is).
- work on an udev rule that detect the physical path, and creates a
symlink /dev/input/mosart-X
- rely on xorg input rules system to detect your devices (though I
don't know when they added the physical path in the configuration
options).

Cheers,
Benjamin



On Thu, Jun 21, 2012 at 4:52 PM, Donald Kayser [off-list ref] wrote:

Hello All,

I am part of development of a product that uses touchscreens extensively. We
have to maintain touchscreen calibration and X Display association across
boots. We support up to six screens, 3 internal to our product, 3 external
to our product. All internal screens have touchscreens with cables that
don't move, so using the device /dev/input/by-path/<devicelink> I could
modify xorg.conf with an InputSection and associate the screen and
touchscreen, include calibration, and every time the user returned, it was
already calibrated and working correctly. It has worked great until we
started adding multi-touch devices. The line of multi-touch devices we are
using is manufactured my MosArt.

I added the defines for the products in my local kernel tree's
driver/hid/hid-ids.h and added the quirk for HID_QUIRK_MULTI_INPUT in
hid-quirks.c. With the kernel 2.6.39.4 and earlier to 2.6.32.n, there is
confusion with the /dev/input/by-path/<devlink>.  These multi-touch devices
show up with four entries in /dev/input/<dev>. From looking at the output of
lsinput, two of the entries have identical information with regards to event
bits. Only one of these identical entries in /dev/input/<dev> actually work;
one reports 13 axis, one reports 3 axis. When the
/dev/input/by-path/<devlink> points to the 'working' /dev/input/<dev> all is
fine. This only happens 50% of the time and with three screens it is not
likely to get all three right on any boot.

So, is this a good place to ask this question? What other information would
be beneficial? I purposely left out a bunch of debug info so not to get too
noisy.

Thanks in advance,
Donald Kayser
linux at kayser dot net
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