Re: Regression from 2.6.26: Hibernation (possibly suspend) broken on Toshiba R500 (bisected)

From: Frans Pop
Date: Thu Dec 04 2008 - 13:00:42 EST

On Thursday 04 December 2008, Linus Torvalds wrote:
> On Thu, 4 Dec 2008, Frans Pop wrote:
> > I've given your patch a try and the few resumes from STR I've done
> > were all successful. That's not 100% conclusive yet, but a nice
> > start. Some info from logs etc. below.
> Ok, but I thought you had a hard time reproducing this _anyway_, even
> with just plain -rc7. No?

Well, I had a failure rate of about 1 in 5-10 resumes originally.

Then I found the 2 workarounds and *with those in place* I got almost 100%
reliable resumes. Now I've removed those workarounds and with either the
revert or your oneliner I still get 100% success.
>From my PoV that is a very definite improvement: the machine now "feels" a
hell of a lot more reliable for critical use.

So I _could_ reproduce it reliably given enough suspend/resume cycles.
But I guess this does support your suspicion that it may be a timing
issue: if the timing happens to be right, the resume succeeds; if it's
wrong I get a dead box.

> Since it's apparently STR, has anybody gotten _anything_ sane out of
> trying to enable PM_TRACE_RTC, and then doing that
> echo 1 > /sys/power/pm_trace

I did try that at the beginning. That's how I ended up removing e1000e
before suspend. See

My next hint was that Matthew Garret, who has the same notebook, was
surprised at my resume problems as he did not see them. So I did a
comparison of our kernel configs and made some changes to mine. From
that I found that a very low value for SND_HDA_POWER_SAVE_DEFAULT (5)
reduced the failure rate to practically zero.

At some point I tried keeping e1000e loaded for a bit, but that quickly
gave me a failure again, so I starting removing it again during suspend.

So I did have some data, but as I got no response on my BR I had no idea
where to go from there. I was really very happy to see Rafael's mail as
his description almost exactly matched what I had been seeing.

I'd be happy to run with unpatched kernels for a while and do some more
pm_traces, but only if someone is going to follow up and interpret the
results for me or provide suggestions for targeted additional debugging.

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