Hi John

On 2011-09-16 11:45 , John Sung wrote:

Dear Daniel,

This is John from PenMount Touch Solutions. I have some question about
the usbtouchscreen driver, and found your email in the source file, so
decide to contact you. Would you help us by answering some questions ?

Note that I have not touched that driver (or the Linux kernel in general)
in quite a while.

Our company have a new product PenMount 6250 touch controller, and
would like to add support to the usbtouchscreen. But we are not sure
if this is what we should do, because the features of PenMount 6250.

That's great to hear.

The PenMount 6250 is a HID device, so it can be supported by the
usbhid driver with single touch. We would like to add the PenMount
6250 multi-touch support. But since it does not use standard
multi-touch HID usages like others does, we cannot use the
hid-multitouch driver.

The PenMount 6250 reports additional information such as touch ID.
However, This ID information is not listed as a HID usage in the
PenMount 6250 HID report descriptor, so
that these data will be dropped by the hid driver. When we look at the
existing usbtouchscreen driver, however, it does not contain any other
multi-touch device support, so we are wondering if adding support to
the usbtouchscreen driver is what we
should do.

I think usbtouchscreen is the wrong place. It has no multitouch support so
far and is basically for all the non-HID devices. hid-multitouch on the
other hand sounds more like the right place. I don't know that driver,
but looking at it, it has some vendor-specific code in it already. So if
your device is basically HID with some extensions, I think it makes sense
to extend hid-multitouch. Another possibility would be an extra HID driver
like hid-wacom or hid-magicmouse.

I don't know much about the HID protocol and these drivers, so I Cc'ed
the lists linux-input and linux-usb...people there will be able to give
you better help than I do :)

Cheers
-daniel