[CPUFREQ] pcc driver should check for pcch method before calling _OSC

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The pcc specification documents an _OSC method that's incompatible with the
one defined as part of the ACPI spec. This shouldn't be a problem as both
are supposed to be guarded with a UUID. Unfortunately approximately nobody
(including HP, who wrote this spec) properly check the UUID on entry to the
_OSC call. Right now this could result in surprising behaviour if the pcc
driver performs an _OSC call on a machine that doesn't implement the pcc
specification. Check whether the PCCH method exists first in order to reduce
this probability.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Signed-off-by: Dave Jones <davej@redhat.com>

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Matthew Garrett 2010-07-20 13:52:00 -04:00 • committed by Dave Jones

parent cad70a6ae5

commit 5d77b85458

1 changed files with 5 additions and 1 deletions

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arch/x86/kernel/cpu/cpufreq/pcc-cpufreq.c

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