Re: [PATCH 0/1] HID: Report Descriptor in Sysfs

[Jiri Kosina]

On Fri, 21 Jan 2011, Alan Ott wrote:

> Well, what I really want is the Usage Page and Usage of the device. For some
> background, I maintain a library called hidapi[1] for accessing HID devices in
> a cross platform way. There are currently four backends, Linux-hidraw,
> Linux-libusb, Mac OS, and Windows.
> 
> I've recently received requests for supporting composite HID devices. Since a
> composite device will show up as multiple devices with the same VID/PID, one
> needs a way to differentiate between its different interfaces. On Windows and
> Mac, the platform HID libraries support getting the Usage Page and Usage of
> each interface. On Linux/libusb I can request the HID report descriptor and
> parse it myself, but I have to claim the interface to do it, and to do that, I
> have to detach the kernel driver. Needless to say, detaching the kernel driver
> is not good, especially when the library is supposed to be just scanning for
> devices.
> 
> For these reasons, it would be really convenient to get the report descriptor
> from sysfs.

In this case, you can still get the report descriptor from hidraw (which 
is parallel to any other HID-bus based kernel driver). Woudl that suit 
your needs?

-- 
Jiri Kosina
SUSE Labs, Novell Inc.
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