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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [PATCH 5/5] husb: rewrite Linux host USB layer,
	fully async operation
Date: Fri, 15 Aug 2008 20:53:26 +0100
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To: qemu-devel@nongnu.org
Cc: kvm@vger.kernel.org, Max Krasnyansky <maxk@kernel.org>

> Given that OHCI is much more complex than UHCI (both the code and the spec)
> I decided to give up on OHCI, at least for now. I noticed Codesourcery
> copyright on OHCI. Did you have anything to do with the OHCI implementation?

Yes, I wrote the current OHCI support, based on some initial patches by 
Gianni.

I found OHCI to be much easier to deal with than than UHCI. The low-level bits 
of the USB protocol are fairly nasty.  UHCI is a cheap and nasty host 
solution, which directly exposes (and requires faking of) all the nasty low 
level details and timing.

OHCI is a higher level interface which I found makes it much easier to 
actually implement things sanely in a virtual environment.

> So we'd definitely need to work on OHCI if it's important for some
> platforms.

I consider OHCI to be important. x86 is abut the only target foolish enough to 
use UHCI.

Paul