For Centaur CPU, the ucode will make sure that each CPU core can keep cache
coherency with each other when the CPU core entering to any C state. So the
cache flush operations when enter C3 is not necessary and will cause large
C3 enter/exit latency.
And the bus master disable operation when CPU core entering C3 state is not
needed too. Because the chipset will automatically do this operation.
Signed-off-by: David Wang <davidw...@zhaoxin.com>
---
arch/x86/kernel/acpi/cstate.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index dde437f..1cd357b 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -51,6 +51,18 @@ void acpi_processor_power_init_bm_check(struct
acpi_processor_flags *flags,
if (c->x86_vendor == X86_VENDOR_INTEL &&
(c->x86 > 0xf || (c->x86 == 6 && c->x86_model >= 0x0f)))
flags->bm_control = 0;
+
+ if (c->x86_vendor == X86_VENDOR_CENTAUR) {
+ /*
+ * on all centaur CPUs, sw need not execute cache flush
operation
+ * when entering C3 type State.
+ *
+ * On all Centaur platforms, sw need not execute ARB_DISABLE
while
+ * entering C3 type state.
+ */
+ flags->bm_check = 1;
+ flags->bm_control = 0;
+ }
}
EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
--
1.9.1
