Hi,
On 21-09-17 16:00, Matt Porter wrote:
On Thu, Sep 21, 2017 at 10:59:08AM +0200, Hans de Goede wrote:
Hi,
On 19-09-17 18:41, Matt Porter wrote:
The Chalkboard Electronics HID Touchscreen is classified as
a tablet device by systemd udev because it has BTN_TOOL_PEN
support. It also reports a resolution of 0 for both X and Y
axes in absinfo. This causes libinput to reject it as an
invalid tablet device.
This quirk reclassifies the device as a touchscreen which
allows it to be added as a valid input device.
Signed-off-by: Matt Porter <mpor...@konsulko.com>
Have you considered adding special handling for this device
to the kernel's hid drivers ? The hid subsys has sub drivers
for device specific handling and if the device never actually
has a pen, then the right fix would be to not make the kernel
export this. Note I assume this is for a so called
"smart" whiteboard for in classes ? If that is the case then
the device may actually have a pen/stylus like device in
some configuration. Some of these smart boards have what
are basically empty whiteboard-marker in multiple colors
and the device may report these as different styluses ...
I hadn't really considered that since this userspace fixup
basically follows the pattern I see for other devices in
systemd's hwdb.
In this case (exporting a wrong event capability) a kernel fix
seems more appropriate to me. In general we try to fix things
as early in the chain as possible. hwdb quirks are more for
things like: Yes this device supports semi-mt and the kernel
exports that info, but the semi-mt coordinates are so unreliable
that we really should just treat it as a single touch device.
Anyways this is just my 2 cents, Peter what do you think,
kernel fix or hwdb ?
Just to clarify, these are not "smartboard"
style devices. They are typical 7-14" touchscreen displays
with HDMI/USB interface from https://www.chalk-elec.com/
Ok, that is good to know, really weird the export a
BTN_TOOL_PEN then.
Regards,
Habs
The updated patch for this is at
https://github.com/systemd/systemd/pull/6880 based on Peter's
earlier comments. It could be solved in the kernel as you
suggest, however it appears that usually that approach is for
very different hid devices with custom protocols (e.g.
logitech-hidpp). I could suppress the pen tool and update absinfo
in a hid-chalkboard.c if that's preferred. There could be an
advantage here for those that aren't using systemd udev.
-Matt
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