Re: [linux-usb-devel] [RFC] HID bus design overview.

Adam Kropelin
2007-04-04T23:35:00Z

Jiri Kosina wrote:
> On Wed, 4 Apr 2007, Adam Kropelin wrote:
>
>> I apologize for picking up this thread late and asking what may be a
>> question with an obvious answer... Will hiddev still exist after
>> hidraw and the HID bus redesign work is done? I have a
>> widely-deployed userspace app that relies on hiddev, and I'm looking
>> for reassurance that it will still work as it always has...
>
> Hi Adam,
>
> hiddev will have to stay for quite some time, exactly because of
> backward compatibility with userspace applications/drivers that use
> it (I am not aware of many of them though, but apparently there are
> some).

Apcupsd is the one on my mind, but I believe there are others.

> I won't allow it to vanish, don't worry.

Thanks!

> We just have to make sure that new users will use hidraw instead, as
> it provides more flexibility for the user, is not dependent on the
> underlying transport protocol, etc.

On Apcupsd we've recently introduced a libusb-based driver that does all
HID parsing in userspace. Not only does that free us from hiddev, it
also frees us from the umpteen other proprietary HID interfaces across
various platforms. Although the hiddev-based driver is still the default
for Linux platforms, I plan to change that in the next major release and
thus begin migrating folks off of hiddev.

I appreciate your pledge to keep hiddev functioning in the mean time :)

--Adam