Re: [PATCH 4/5] HID: autoload hid-multitouch as needed

From: Jiri Kosina
Date: Tue Mar 13 2012 - 12:13:32 EST


On Tue, 13 Mar 2012, Stéphane Chatty wrote:

> > Let me answer by a bit of history here. Originally, there have been
> > two copies of HID code in the kernel -- one for USB HID devices, one
> > for Bluetooth HID devices. The parsers were not kept in sync, and
> > there was a lot of code duplication, creating quite some mess.
> >
> > What I did back then in 2006 was that I have extracted the abstract HID
> > parts into HID core, and made it transport-independent in principle, so
> > that both USB HID and Bluetooth HID shared the common infrastructure,
> > while implementing different transport protocols.
> >
> > Then we extended it a little bit further, making HID core a proper bus, to
> > which individual drivers (independently on underlying transport protocol
> > used) can register.
> >
> > Currently there are just Bluetooth (hidp) and USB (usbhid) transport
> > implementations, with HID core being transport independent.
> >
> > Hope this helps,
>
> Very useful clarification, thanks. Now, I guess I understand why Marcel
> wants to keep hidp in bluetooth/. And, to be honest, things would have
> been clearer to me when I explored the handling of the USB/HID class if
> I had found a hid (or usbhid) directory in usb/ rather than a usbhid
> subdirectory in hid/: it did not make the above situation very obvious
> to me. Don't you think we could go along with Marcel and move usbhid to
> usb/?

It seemed to be convenient back then, and it's still convenient for me in
some sense, as I am maintaining both HID core and USB HID, but bluetooth
guys are maintaining the bluetooth transport.

But I don't have strong opinion either way, I can as well move usbhid to
drivers/usb and maintain it there (will need to talk to Greg about it
first of course). But frankly, I don't see it making things magically
clear for everyone :)

--
Jiri Kosina
SUSE Labs
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