From mboxrd@z Thu Jan 1 00:00:00 1970 In-Reply-To: <762A181C0D966E459A2EB3B810142C7703861518@nmrusdunsx12.nmrlan.net> References: <762A181C0D966E459A2EB3B810142C7703861518@nmrusdunsx12.nmrlan.net> Mime-Version: 1.0 (Apple Message framework v618) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: <75D875A6-DC05-11D8-9220-003065F9B7DC@embeddededge.com> Cc: "'Robert P. J. Day'" , Embedded Linux PPC list From: Dan Malek Subject: Re: random ramblings on 8xx patches (long and tedious :-) Date: Thu, 22 Jul 2004 13:35:01 -0400 To: "Wells, Charles" Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: On Jul 22, 2004, at 1:10 PM, Wells, Charles wrote: > ....... The real problem is that the > MPC850 USB controller was designed for target-mode applications and not > host-mode applications. Host-mode in the MPC850 is, at best, an > after-thought. That's true. Having been a part of the early development of all of the 8xx parts, there were lots of requirements that changed once the parts "hit the street." > 0. The MPC850 USB controller is neither of the popular USB 1.1 > implementation models (UHCI or OHCI). It's not the only one. I think there are more embedded controllers that are not UHCI/OHCI than those that are. Since we work in the source code world, it hasn't really been much of a problem. > ..... I haven't timed it, but I suspect the microcode patch > has trouble meeting this spec. as well. It does get a whole lot > closer than > a software-only solution, though. The microcode patch works quite well. > There's a bunch of other detailed problems that I won't bore everyone > with. > Bottom line: Don't expect too much out of the MPC850 USB controller in > host-mode. There are Linux versions of software that work fine in many applications. USB in general doesn't rate high on my list of engineering successes. I'm never surprised when I plug something in to any kind of system and it doesn't work. -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/