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Re: Porting Au1x000 USB host controller on u-boot

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Subject: Re: Porting Au1x000 USB host controller on u-boot
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Date: Thu, 04 May 2006 21:16:19 +0400
Cc: Rodolfo Giometti <giometti@linux.it>, Linux-MIPS <linux-mips@linux-mips.org>
In-reply-to: <445A347A.5050507@ru.mvista.com>
Organization: MontaVista Software Inc.
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20060504095341.GB19913@gundam.enneenne.com> <445A347A.5050507@ru.mvista.com>
Sender: linux-mips-bounce@linux-mips.org
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Hello, I wrote:

I'm trying to implement support for USB host into u-boot. I
initialized the USB controller just as linux does, the EDs and the TDs
look like good in memory but the controller seems not well reading
them and on the bus I see random USB messages...

I think that there could be some problem on memory coherency... some
suggestion?

try to disable USB controller's DMA coherency in the USB enable register (there's a related errata in all Au1xx0 family) -- the Linux driver doesn't do this though, and this shouldn't matter unless you're modifying USB buffers on the fly. :-)

AND make sure every buffer/TD/ED is written back / invalidated from cache before the OHCI accesses them since the cache coherency on Au1xx0 is b0rken!

WBR, Sergei


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