Messages in this thread | | | Date | Sat, 16 Oct 2010 04:25:59 -0400 (EDT) | From | Len Brown <> | Subject | Re: [PATCH] intel_idle: PCI quirk to prevent Lenovo Ideapad s10-3 boot hang |
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> > > > we check (and clear) that bit only if the acpi tables > > > > tell us to do so. > > > > > > Do the tables tell us to do so on this platform? > > > > In this configuration, yes, otherwise acpi_idle > > would have failed in exactly the same way. > > So why is intel_idle not paying attention to what the platform is > requesting?
ACPI's BM_STS mechanism is obsolete, and is fundmentally incompatible with a tickless OS. The status bit is a NO-OP on most modern chip-sets under normal conditions. However, even when not a NO-OP, it is supposed to be just an indicator and clearing it should have no functional effect on the hardware except to re-arm the hardware that looks for BM_STS.
Clearing BM_STS on the NM10 chipset at boot-time to make the system boot has nothing to do with "what the platform is requesting". It is a workaround for a platform bug that is randomly masked by how the behaviour of the legacy ACPI OS.
intel_idle it knows nothing about ACPI, and it never will.
thanks, Len Brown, Intel Open Source Technology Center
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