Re: [PATCH RESEND] USB HID: Add ID for eGalax Multitouch used in JooJoo tablet

On Fri, 13 Aug 2010, Stéphane Chatty wrote:

In summary this is a new kind of panel with an unusual HID prototol and the
hid-egalax driver fails at producing a proper event sequence. The major issue
here is that the key to resolving the problem does *not* lie in the driver:
SYNC messages are produced in hid-input.c and drivers cannot block them. To
address this, one would need to make the <HID event> -> <input event> + <sync>
mapping less systematic. This could converge with the efforts required if we
were to have a more generic management of multitouch devices (we need one
driver for each device because hid-core.c was not designed with this kind of
device in mind).

My suggestions:
- accept the patch, after adding a few comments in the code about this device
requiring future care for its 'serial' protocol.
- start thinking about what changes are required in hid-input and/or hid-core
for a more generic management of multitouch devices.

Hi Stephane,

thanks for the analysis. How do devices in their report descriptor 
describe the fact whether the events should be interleaved by sync or not?

We definitely could create a specialized version of 
hidinput_report_event() for certain reports, which wouldn't issue the 
input_sync() call, but I wonder what is the distinguishing factor.

-- 
Jiri Kosina
SUSE Labs, Novell Inc.
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