From: Len Brown <len.brown@intel.com>
Date: Thu, 22 Jul 2010 21:23:10 +0000 (-0400)
Subject: ACPI: create "processor.bm_check_disable" boot param
X-Git-Tag: v2.6.35~38^2~2^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d3e7e99f2faf9f44ec0a3379f735b41c9173dfa1;p=pandora-kernel.git

ACPI: create "processor.bm_check_disable" boot param

processor.bm_check_disable=1" prevents Linux from checking BM_STS
before entering C3-type cpu power states.

This may be useful for a system running acpi_idle
where the BIOS exports FADT C-states, _CST IO C-states,
or _CST FFH C-states with the BM_STS bit set;
while configuring the chipset to set BM_STS
more frequently than perhaps is optimal.

Note that such systems may have been developed
using a tickful OS that would quickly clear BM_STS,
rather than a tickless OS that may go for some time
between checking and clearing BM_STS.

Note also that an alternative for newer systems
is to use the intel_idle driver, which always
ignores BM_STS, relying Linux device drivers
to register constraints explicitly via PM_QOS.

https://bugzilla.kernel.org/show_bug.cgi?id=15886

Signed-off-by: Len Brown <len.brown@intel.com>
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