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authorLen Brown <len.brown@intel.com>2010-01-19 23:10:04 -0500
committerLen Brown <len.brown@intel.com>2010-01-20 00:54:15 -0500
commita6d72c189f6c4292ba1a323e8af24083790529f8 (patch)
tree4ae87d681a844997f94ff987d060b2c44dac30ed /drivers/acpi
parent5d76b6f6c17572e662f5c99c2023adae92100855 (diff)
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ACPI: allow C3 > 1000usec
Do for C3 what the previous patch did for C2. The C2 patch was in response to a highly visible and multiply reported C-state/turbo failure, while this change has no bug report in-hand. This will enable C3 in Linux on systems where BIOS overstates C3 latency in _CST. It will also enable future systems which may actually have C3 > 1000usec. Linux has always ignored ACPI BIOS C3 with exit latency > 1000 usec, and the ACPI spec is clear that is correct FADT-supplied C3. However, the ACPI spec explicitly states that _CST-supplied C-states have no latency limits. So move the 1000usec C3 test out of the code shared by FADT and _CST code-paths, and into the FADT-specific path. Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/processor_idle.c21
1 files changed, 11 insertions, 10 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 8f6da9acc8e..2c543b42eb1 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -316,6 +316,17 @@ static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
pr->power.states[ACPI_STATE_C2].address = 0;
}
+ /*
+ * FADT supplied C3 latency must be less than or equal to
+ * 1000 microseconds.
+ */
+ if (acpi_gbl_FADT.C3latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "C3 latency too large [%d]\n", acpi_gbl_FADT.C3latency));
+ /* invalidate C3 */
+ pr->power.states[ACPI_STATE_C3].address = 0;
+ }
+
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"lvl2[0x%08x] lvl3[0x%08x]\n",
pr->power.states[ACPI_STATE_C2].address,
@@ -533,16 +544,6 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
return;
/*
- * C3 latency must be less than or equal to 1000
- * microseconds.
- */
- else if (cx->latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
- ACPI_DEBUG_PRINT((ACPI_DB_INFO,
- "latency too large [%d]\n", cx->latency));
- return;
- }
-
- /*
* PIIX4 Erratum #18: We don't support C3 when Type-F (fast)
* DMA transfers are used by any ISA device to avoid livelock.
* Note that we could disable Type-F DMA (as recommended by