Messages in this thread Patch in this message | | | Date | Wed, 11 Aug 2010 16:55:16 -0700 | From | Greg KH <> | Subject | [095/111] ACPI: Fix regression where _PPC is not read at boot even when ignore_ppc=0 |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Darrick J. Wong <djwong@us.ibm.com>
commit 455c0d71d46e86b0b7ff2c9dcfc19bc162302ee9 upstream.
Earlier, Ingo Molnar posted a patch to make it so that the kernel would avoid reading _PPC on his broken T60. Unfortunately, it seems that with Thomas Renninger's patch last July to eliminate _PPC evaluations when the processor driver loads, the kernel never actually reads _PPC at all! This is problematic if you happen to boot your non-T60 computer in a state where the BIOS _wants_ _PPC to be something other than zero.
So, put the _PPC evaluation back into acpi_processor_get_performance_info if ignore_ppc isn't 1.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: Len Brown <len.brown@intel.com> Acked-by: Jeff Mahoney <jeffm@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/acpi/processor_perflib.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/acpi/processor_perflib.c +++ b/drivers/acpi/processor_perflib.c @@ -356,7 +356,11 @@ static int acpi_processor_get_performanc if (result) goto update_bios; - return 0; + /* We need to call _PPC once when cpufreq starts */ + if (ignore_ppc != 1) + result = acpi_processor_get_platform_limit(pr); + + return result; /* * Having _PPC but missing frequencies (_PSS, _PCT) is a very good hint that
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