Re: Pegasos2 hangs during usb_discover()

[Matt Thomas <matt%3am-software.com@localhost>]

On Dec 15, 2010, at 2:25 PM, Frank Wille wrote:

> Some more information on this problem. Maybe somebody has an idea:
> 
> The Pegasos enters an infinite loop in usb_allocmem() due to a corrupted
> usb_frag_freelist entry, which was just allocated in the previous call.
> 
> Probably caused by a USB DMA transfer, the block, offs and next fields of
> the head usb_frag_dma node are trashed. This is an uhci controller.
> 
> Is it possible to do USB transfers without DMA for testing? I see not many
> possibilities to debug it further.
> 
> USB worked some months ago. No other PPC port seems to be affected. Are
> other ofppc (non-Pegasos) machines affected? Any information is welcome.

I've found usb_mem.c fragments to be a problem on many ppc.
I just checked in a workaround which seems to work for me.  Maybe it
will work for you.

I blame the lack of problem bus_dma for this problem but I have no proof.