Messages in this thread Patch in this message | | | Date | Thu, 30 Apr 2009 10:54:14 +0100 | From | Matthew Garrett <> | Subject | Re: [PATCH v2] acpi: Fix regression where _PPC is not read at boot even when ignore_ppc=0 |
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On Thu, Apr 30, 2009 at 09:25:56AM +0200, Ingo Molnar wrote:
> OTOH, if you rely on me figuring out which patch to revert and what > to do, it will take an indeterminate amount of time - together with > all the other items in my 'would be nice to hack on, given a bit of > free time' queue :)
Here's Darrick's patch:
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.
This second version restores the correct function call, which simplifies the patch. I apologize for the churn and the poor eyesight.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> ---
drivers/acpi/processor_perflib.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c index cafb410..85af717 100644 --- a/drivers/acpi/processor_perflib.c +++ b/drivers/acpi/processor_perflib.c @@ -348,7 +348,11 @@ static int acpi_processor_get_performance_info(struct acpi_processor *pr) 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 -- Matthew Garrett | mjg59@srcf.ucam.org
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