cvs commit: src/sys/dev/pci pci.c
nate at root.org
Mon Sep 19 16:28:39 PDT 2005
M. Warner Losh wrote:
> In message: <432D9F4B.9080902 at root.org>
> Nate Lawson <nate at root.org> writes:
> : Joao Barros wrote:
> : > I was reading the Release Notes for 6.0 on
> : > http://www.freebsd.org/relnotes/6-STABLE/relnotes/i386/article.html
> : > and noticed:
> : >
> : > 2.2.2 Hardware Support
> : >
> : > The acpi(4) driver now turns the ACPI and PCI devices off or to a
> : > lower power state when suspending, and back on again when resuming.
> : > This behavior can be disabled by setting the debug.acpi.do_powerstate
> : > and hw.pci.do_powerstate sysctls to 0.
> : >
> : > Given this is the same tunable you changed back to 0 by default, does
> : > that "when resuming" has anything to do with this last commit? If so,
> : > it could still be mentioned the other way around, allowing people
> : > wanting to, to enable the tunable :)
> : You bring up a different point also, which is that ACPI should probably
> : be set to match this same default for release.
> Actually, all that the do_powerstate stuff in pci land does is turn
> off the devices when no driver is attached. We always turn them back
> on on resume.
That's not how the acpi powerstate support works. It turns off devices
not allowed in a given Sx state while suspending and turns them on again
in resume. For instance, if _S3D says a given device must be in D1
while we sleep in S3, we power down that device to D1 in the suspend
path and back up to D0 (running) in the resume path.
I haven't heard of any problems, but for consistency I was asking if
this should be disabled also in the release.
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