On Wed, Oct 20, 2021 at 1:28 PM Alistair Francis [off-list ref] wrote:

On Wed, Oct 20, 2021 at 12:14 PM Dmitry Torokhov
[off-list ref] wrote:

quoted

On Wed, Oct 20, 2021 at 11:44:50AM +1000, Alistair Francis wrote:

quoted

On Wed, Oct 20, 2021 at 11:05 AM Dmitry Torokhov
[off-list ref] wrote:

quoted

On Wed, Oct 20, 2021 at 09:33:13AM +1000, Alistair Francis wrote:

quoted

On Tue, Oct 19, 2021 at 11:51 AM Dmitry Torokhov
[off-list ref] wrote:

quoted

We already have touchscreen-inverted-x/y defined in
Documentation/devicetree/bindings/input/touchscreen/touchscreen.yaml,
why are they not sufficient?

The touchscreen-* properties aren't applied to HID devices though, at
least not that I can tell.

No, they are not currently, but that does not mean we need to establish
a new set of properties (property names) for HID case.

I can update the names to use the existing touchscreen ones.

Do you have a hint of where this should be implemented though?

Right now (without "HID: wacom: Add support for the AG14 Wacom
device") the wacom touchscreen is just registered as a generic HID
device. I don't see any good place in hid-core, hid-input or
hid-generic to invert the input values for this.

I think the transformation should happen in
hid-multitouch.c::mt_process_slot() using helpers from
include/linux/input/touchscreen.h

Thanks for the help!

I have managed to get the device to be a hid-multitouch (instead of
hid-generic).

I also think I have figured out a way to get the properties to
hid-multitouch from the i2c-hid device. It requires a change to
touchscreen.c, but it's not a big change.

The main problem now is that hid-multitouch.c::mt_process_slot() isn't
actually called. The code just calls input_sync() from
hid-multitouch.c::mt_report(). It doesn't get to mt_process_slot() due
to rdata->is_mt_collection not being true. Setting
rdata->is_mt_collection to true causes userspace not to see the wacom
input any more.

hid-multitouch now only handles the mutltitouch part. Everything else
is handled in hid-input.c
So if the device is just presenting a stylus to the user space, you
better not use hid-multitouch at all, but hid-generic.

Cheers,
Benjamin

Alistair

quoted

I think the more challenging question is to how pass/attach struct
touchscreen_properties * to the hid device (i expect the properties will
be attached to i2c-hid device, but maybe we could create a sub-node of
it and attach properties there.

Thanks.

--
Dmitry