Re: EHCI Regression in 2.6.23-rc2

[David Brownell <david-b@pacbell.net>]

On Monday 13 August 2007, Stuart_Hayes@dell.com wrote:
> With the VIA controller I have,

Which kind is that?  The VT6202 is buggy as all get-out, and
they sold a *LOT* of those discrete chips for use in add-on PCI
cards.  We generally warn people away from those.  A more current
version is the VT6212, which was much more usable.  (If it says
EHCI 0.95, it's a VT6202... their EHCI 1.0 chips were much better.)


> after I set the "inactivate" bit, I 
> eventually see the controller set bit 1 in the overlay token
> (SplitXstate), indicating that it's running the transaction, and, a
> couple microframes later, it clears that bit again.  The transaction is
> not inactivated.

> ...

> Perhaps for now the best thing would just be to bypass the EHCI CPU
> frequency notifier code (i.e., my patch) for VIA EHCI controllers, since
> they are broken.  Would a hard-coded blacklist (just an "if
> (manufacturer==VIA)..." type thing) be OK?

Yes ... although if you don't need to blacklist their EHCI 1.0 chips
don't do it.  (Any VIA EHCI integrated into a southbridge is going
to follow spec rev 1.0 pretty well, modulo idiosyncratic timings.)


> I've also acquired a card with an NEC EHCI controller on it, which I'm
> going to look at while I'm into it...

Another case where there are a lot of add-on "EHCI 0.95" cards; but
in this case the quirks were less significant.

- Dave