svn commit: r188814 - head/sys/dev/acpica
Andriy Gapon
avg at freebsd.org
Thu Feb 19 10:21:25 PST 2009
on 19/02/2009 16:39 Andriy Gapon said the following:
> Author: avg
> Date: Thu Feb 19 14:39:52 2009
> New Revision: 188814
> URL: http://svn.freebsd.org/changeset/base/188814
>
> Log:
> acpi_cpu: fixup for PIIX4E PCI config related to C2
>
> This is triggered only if BIOS configures ACPI_BITREG_BUS_MASTER_RLD
> aka BRLD_EN_BM to 1.
> Rationale:
> 1. we do not support C3 on PIIX4E
> 2. bus master activity need not break out of C2 state
> 3. because of CPU_QUIRK_NO_BM_CTRL quirk we may reset bus master
here should have been "never" --------------------^^^
> status which would result in immediate break out from C2
>
> So if you have seen
> cpu0: too many short sleeps, backing off to C1
> with this chipset before you may want to try cx_lowest of C2 again.
--
Andriy Gapon
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