Re: [PATCH 084/123] USB: fix up suspend and resume for PCI host controllers

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On Sat, 17 Jan 2009, Benjamin Herrenschmidt wrote:

> > Ben, we need to check with you on this also.  These patches we have
> > been throwing around move the code to disable and enable the PPC_PMAC
> > ASIC clocks for USB.  Can that code execute safely at any time while
> > the host controller isn't running?  Is it okay to execute the code
> > with interrupts disabled?
> 
> Wow, that's digging old stuff I haven't touched for some time :-)
> 
> So I think running the pmac hooks with IRQs off might be ok. They have
> delays but they use mdelay() not msleep().
> 
> As to when it is safe to run that code, it isn't a trivial answer. I'd
> say any time after it's been suspended and before it's resumed sounds
> about right, but my experience with those earlier Apple built-in OHCIs
> is that they are -very- sensitive to random environmental conditions
> when suspending/resuming and if -anything- goes wrong, they start
> happily scribbling all over system memory when suspended :-(
> 
> So I think it's going to boil down to testing. Might be useful to find
> somebody with one of the really old powerbooks, I see if I can find that
> around the lab here, mine is dead.
> 
> Do you have a git tree I can pull to test your stuff ?

Not exactly.  Just try this patch:

	http://marc.info/?l=linux-kernel&m=123184641714487&w=2

with vanilla 2.6.29-rc1 or rc2.

Alan Stern

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