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

Le 12 mars 2012 à 23:21, Jiri Kosina a écrit :

> On Mon, 12 Mar 2012, Stéphane Chatty wrote:
>> Just in case it makes a difference, I knew nothing about HIDP when I
>> wrote the message above. My point was rather that hid looks like a bus
>> to which several transport layers can connect (USB, Bluetooth, ZigBee,
>> etc), and that having USB-specific code in hid/ (as opposed to having it
>> in usb/) seems biased towards USB. I was (and am still) wondering how
>> much it limits future uses of the hid core by making it USB-dependent.
>> In other words: is the hid core generic enough or are there steps to
>> take to make it more generic wrt transport layers? If we are talking
>> about restructuring parts of it, this seems like the right time to ask
>> :-)
> 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/?


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