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authorLen Brown <len.brown@intel.com>2010-07-22 16:54:27 -0400
committerLen Brown <len.brown@intel.com>2010-07-22 16:54:27 -0400
commit718be4aaf3613cf7c2d097f925abc3d3553c0605 (patch)
treefeaf57a034684a6742198a5cf10e8e05ed1cb10f /include/acpi
parentf4b23cc2d5dc78ef5acbc529eb1219cc41eb5b96 (diff)
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ACPI: skip checking BM_STS if the BIOS doesn't ask for it
It turns out that there is a bit in the _CST for Intel FFH C3 that tells the OS if we should be checking BM_STS or not. Linux has been unconditionally checking BM_STS. If the chip-set is configured to enable BM_STS, it can retard or completely prevent entry into deep C-states -- as illustrated by turbostat: http://userweb.kernel.org/~lenb/acpi/utils/pmtools/turbostat/ ref: Intel Processor Vendor-Specific ACPI Interface Specification table 4 "_CST FFH GAS Field Encoding" Bit 1: Set to 1 if OSPM should use Bus Master avoidance for this C-state https://bugzilla.kernel.org/show_bug.cgi?id=15886 Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'include/acpi')
-rw-r--r--include/acpi/processor.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index da565a48240..a68ca8a11a5 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -48,7 +48,7 @@ struct acpi_power_register {
u8 space_id;
u8 bit_width;
u8 bit_offset;
- u8 reserved;
+ u8 access_size;
u64 address;
} __attribute__ ((packed));
@@ -63,6 +63,7 @@ struct acpi_processor_cx {
u32 power;
u32 usage;
u64 time;
+ u8 bm_sts_skip;
char desc[ACPI_CX_DESC_LEN];
};