Re: [net-next 5/9] e1000e: Disable ASPM L1 on 82574

[Nix <nix@esperi.org.uk>]

On 3 May 2012, Carolyn Wyborny told this:

> It would be good to know why/how your system is re-enabling the
> setting. The problem is not solvable in firmware unfortunately and is
> somewhat platform dependent. MMIO-tracer might be used to try and see

I entirely forgot about that tool! *Definitely* worth trying.

I'll give it a try this weekend.

> when the re-enabling config space is written, but it might be too
> heavyweight for a live production system.

Given that the re-enabling happens at around the same time as the boot
scripts finish running (it's done by the time I can log in), that's not
going to be a problem. Hence my speculation that it's being re-enabled
when the interface stabilizes (which is, of course, asynchronous) or
something like that.

> I am also working on a patch to the driver to detect the condition and
> then do a slot reset to avoid a whole system reboot. Would you be
> willing to test it in your problem system?

Yes, definitely. The whole-system reboot is irritating because the
system is headless, and with its NICs dead that means a big red switch
to reboot when this problem strikes, which gives me the heebie-jeebies
:)

(Turning off ASPM definitely completely fixes it, so it *is* this bug.
It's just getting the disabling to stick that's proving tricky.)

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