From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Brook 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 Message-ID: <200808152053.27587.paul@codesourcery.com> References: <200808151524.54015.paul@codesourcery.com> <48A5D32E.2030208@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Max Krasnyansky , kvm@vger.kernel.org To: qemu-devel@nongnu.org Return-path: Received: from mail.codesourcery.com ([65.74.133.4]:34002 "EHLO mail.codesourcery.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753910AbYHOTxa (ORCPT ); Fri, 15 Aug 2008 15:53:30 -0400 In-Reply-To: <48A5D32E.2030208@kernel.org> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: > 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