Re: new mail: USB controller problem on MIPSEL embedded board

> http://forums.viaarena.com/messageview.aspx?catid=16&threadid=73502&enterthread=y

Interesting, so that "performance drops after starting EHCI"
issue shows up with MS-Windows too.  Now all we need is to
have someone throw a logic analyser on a PCI bus that's
experiencing that problem, and maybe we can get clues... :)

That page *does* suggest the VIA parts don't obey chunks of
the PCI spec ... it's not just EHCI they have problems with.


On Friday 24 August 2007, Alan Stern wrote:
> 
> > # cat /sys/class/usb_host/usb_host1/registers
> > bus pci, device 0000:00:01.2 (driver 10 Dec 2004)
> > EHCI Host Controller
> > EHCI 1.00, hcd state 1
> > ownership 00000001
> > SMI sts/enable 0xc0080000
> > structural params 0x00002204
> > capability params 0x00006872
> > status 8008 Async FLR
> > command 010009 (park)=0 ithresh=1 period=256 RUN
> > intrenable 37 IAA FATAL PCD ERR INT
> > uframe 2cac
> > port 1 status 001000 POWER sig=se0
> > port 2 status 001000 POWER sig=se0
> > port 3 status 001000 POWER sig=se0
> > port 4 status 001000 POWER sig=se0
> > irq normal 550418 err 13 reclaim 2079 (lost 1403)
> > complete 4361 unlink 398
> 
> I wouldn't trust that "lost" number too much.  But it could be 
> indicative of the larger problem.

If the number of "lost" reclaims is nonzero, it just means
that some IRQs which *should* have arrived never got there.
(There's a potential race which could also cause that to be
nonzero, but we've never seen evidence of it happening.)

It's some kind of erratum, ISTR only observed on VIA chips.
Unfortunately, even when people from VIA were communicating
with me (as this driver was being written), they never went
so far as to provide relevant hardware specs/errata.

- Dave

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