Re: suspend/hibernation regression between 2.6.19 and 2.6.20 w/ Thinkpad T41

[Toralf Förster]

Am Montag, 6. August 2007 16:36 schrieb Henrique de Moraes Holschuh:
> On Mon, 06 Aug 2007, Toralf Förster wrote:
> > Am Montag, 6. August 2007 00:29 schrieb Pavel Machek:
> > > Yes, I seen similar reports. Does it happen in all shutdown mode and
> > > 2.6.22? Does it happen   in platform mode in 2.6.19?
> > 
> > I can reproduce this behaviour by doing the following with kernel 2.6.20 :
> > 
> > 1. <Fn>+<F4>   - the systems sleeps within RAM
> > 2. <Fn>             - the systems wakes up
> > 3. <Fn>+<F12> - the systems hibernates to disk
> > 4. <power>       - systems wakes up
> > 5. <Fn>+<F4>   - the systems sleeps within RAM
> > 
> > Now pressing <Fn> doesn't wake up the system, I have to press the power button
> > for that instead.
> 
> The resume path for suspend to disk is very different (for the firmware, at
> least) than the resume path from sleep-to-RAM.  One of them goes through a
> system shutdown and cold boot (S5) or whatever-boot (S4 - who knows if it is
> the same as a cold boot in a given thinkpad model? It doesn't have to be!).
> 
> The firmware *knows* when you press Fn+F4/FN+F12, and recalls that. That's
> why you can't get multiple hot key presses from pressing Fn+F4 or FN+F12
> until you actually do an ACPI wake-up.
> 
> While you are just doing S3, all that state is preserved without fuss. But
> S5 does not preserve anything, and S4 is anyone's guess.  Numerous thinkpad
> BIOS fixes in the past were releated to such problems, so if you are not
> using the latest BIOS for your model, your first duty is to upgrade it and
> try again.
> 
> IMHO, probably some ACPI state is being lost by the BIOS because of the
> sleep-to-disk.  I don't know how sleep-to-disk plays with the ACPI NV areas,
> and ACPI data areas from the BIOS, so I can't help much there.
> 
> And, mind you, I am *not* sure one is supposed to be able to wake up
> thinkpads using Fn.  It might be in fact a bug that we can do it.  One has
> to at the very least verify whether it happens in Windows as well.
> 
> However, the following events *are* to wake a thinkpad up from S3:
> 	1. ACPI wake devices
> 	2. Dock or bay eject buttons/lever being actuated
> 	3. Brief press on power button
> 
> You can check if (2) is still working. If both Fn and (2) stop working, we
> can be sure we have a bug in Linux.  (2) is useful because it is reported
> inside the ACPI firmware mostly through the same codepaths.
> 
> > BTW I tried to test the latest git-sources -rc2 but the <Fn> keys do not work
> > anymore with the thinkpad-acpi feature (neither as module nor if compiled into).
> 
> Don't enable the input layer by default in thinkpad-acpi Kconfig.  A patch
> to change that to default to N has already been sent to Len Brown, but it
> has not been merged yet.
> 

Because I
(1) use the latest BIOS and
(2) I'm able to wake up a suspended system via <Fn> under Windows XP (yes, dual
    boot system I need it at work) regardless whether I previously hibernated
    the system (under Windows XP) or not

I bisected this regression (rather of a feature than a bug, or ?) between
the 2 tags v2.6.19 and v2.6.20 (~2400 commits, I read a good book in the
meanwhile) and found :

last good commit : 7e244322cd4ea361ef9ee623b3fcb4d9f4ff841c
first bad commit: cfee47f99bc14a6d7c6b0be2284db2cef310a815

I double checked these 2 commits - here's the first commit after which <Fn>
doesn't wake up my system from suspend state after it was (at least one time
before) hibernated:

commit cfee47f99bc14a6d7c6b0be2284db2cef310a815
Merge: 7e24432... 9185cfa...
Author: Len Brown <len.brown@xxxxxxxxx>
Date:   Sat Dec 16 01:01:18 2006 -0500

    Pull bugfix into test branch

    Conflicts:

        kernel/power/disk.c


-- 
MfG/Sincerely

Toralf Förster

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