On Thursday 20 September 2007 17:55, Linus Torvalds wrote:
>
> On Thu, 20 Sep 2007, Linus Torvalds wrote:
> >
> > (Btw, the above commit message points to just my response with a testing
> > patch to the real email: the actual explanation of the INSANE ordering is
> > from Len Brown in
> >
> > https://lists.linux-foundation.org/pipermail/linux-pm/2006-November/004161.html
> >
> > and there Len claims that we *must* wake up CPU's early).
>
> ..and points to commit 1a38416cea8ac801ae8f261074721f35317613dc which in
> turn talks about http://bugzilla.kernel.org/show_bug.cgi?id=5651
>
> Howerver, it seems that bugzilla entry may just be bogus. It talks about
> "it appears that some firmware in the future may depend on that sequence
> for correction operation"
>
> Len, Shaohua, what are the real issues here?
Intel's reference BIOS for Core Duo performs some re-initialization
in _WAK that will get blow away if INIT follows _WAK.
IIR, it is related to re-initializing the thermal sensors.
I opened bug 5651 when the BIOS team informed me of this issue.
Yes, bringing a processor offline and then online again w/o
an intervening suspend or reset would not evaluate _WAK,
and thus may still run into the issue.
I don't know if this is a widespread issue and a commonly
used BIOS hook, or if it is specific to certain processors.
-Len
> It would indeed be nice if we could just take CPU's down early (while
> everything is working), and run the whole suspend code with just one CPU,
> rather than having to worry about the ordering between CPU and device
> takedown.
>
> That said, at least with STR, the situation is:
>
> 1) suspend_console
> 2) device_suspend(PMSG_SUSPEND) (== ->suspend)
> 3) disable_nonboot_cpus()
> 4) device_power_down(PMSG_SUSPEND) (== ->suspend_late)
> 5) pm_ops->enter()
> 6) device_power_up() (== ->resume_early)
> 7) enable_nonboot_cpus()
> 8) pm_finish()
> 9) device_resume() (== ->resume
> 10) resume_console
>
> So if we agree that things like timers etc should *never* be suspended by
> the early suspend, and *always* use "suspend_late/resume_early", then at
> least STR should be ok.
>
> And I think that's a damn reasonable thing to agree on: timers (and
> anything else that CPU shutdown/bringup could *possibly* care about)
> should be considered core enough that they had better be on the
> suspend_late/resume_early list.
>
> Thomas, Rafael, can you verify that at least STR is ok in this respect?
>
> Linus
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