Re: Porting Au1x000 USB host controller on u-boot

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello,

Rodolfo Giometti 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?

    Be sure to set Config0.OD (bit 19), it's proven to fix the USB-related 
lockups on Au1500 at least. See arch/mips/common/cputable.c for the CPU 
steppings where it must be set to mask various errata. Also, 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. :-)
    Also, note that this magic bit may be write only, so make sure it's set on 
every write to CP0 Config0 reg. See this patch:

http://www.linux-mips.org/archives/linux-mips/2006-03/msg00243.html

> Thanks,
> 
> Rodolfo

WBR, Sergei