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Date: Sat, 01 Jan 2005 23:19:13 +0100
From: Sylvain Munaut <tnt@246tNt.com>
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To: Benny Liu <benny@cellvision.com.cn>
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Cc: linuxppc-dev@ozlabs.org
Subject: Re: isochronous mode of USB audio device on MPC5200
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Hi Benny


What version of the kernel ?


In the last 2.4 I built ( quite a while ago ... ) there was a flaw
in the handling of the hwPSW field in the OHCI driver when on big-endian
platform. Since this field is only used fot Isochronous the problem
didn't show up before.

The fields were assume by the kernel to be in this order

hwPSW[0]
hwPSW[1]
hwPSW[2]
hwPSW[3]
...

But in fact since the figure in ohci spec shows this array not as an
array of 16bits fields but as an array of 32bits integer, each containing
two hwPSW[] in little endian order, they ended up implemented in the order

hwPSW[1]
hwPSW[0]
hwPSW[3]
hwPSW[2]
...

(fscked up isn't it ? ;)


And that was not taken into account ...


I notified W.Denk about the problem a while ago, don't know if any
action has been taken.




Sylvain Munaut


Benny Liu wrote:

> Hi, everyone, happy new year!
> Did anyone try usb audio device or other isochronous mode usb devices
> on Icecube board(Motorola MPC5200)?
> I tried, but it reports the following message:
> /"host/usb-ohci.c: OHCI Unrecoverable Error, controller usb-0 disabled"/
> After this message, the host controller is disabled.
> Thanks a lot.
>
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