ACPI: Use the ARB_DISABLE for the CPU which model id is less than 0x0f.

Currently, ARB_DISABLE is a NOP on all of the recent Intel platforms.
For such platforms, reduce contention on c3_lock by skipping the fake
ARB_DISABLE.

The cpu model id on one laptop is 14. If we disable ARB_DISABLE on this box,
the box can't be booted correctly. But if we still enable ARB_DISABLE on this
box, the box can be booted correctly.

So we still use the ARB_DISABLE for the cpu which mode id is less than 0x0f.

http://bugzilla.kernel.org/show_bug.cgi?id=14700

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: Pallipadi, Venkatesh <venkatesh.pallipadi@intel.com>
cc: stable@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 59cdfa4..2e837f5 100644 (file)
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -48,7 +48,7 @@ void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
         * P4, Core and beyond CPUs
         */
        if (c->x86_vendor == X86_VENDOR_INTEL &&
-           (c->x86 > 0xf || (c->x86 == 6 && c->x86_model >= 14)))
+           (c->x86 > 0xf || (c->x86 == 6 && c->x86_model >= 0x0f)))
                        flags->bm_control = 0;
 }
 EXPORT_SYMBOL(acpi_processor_power_init_bm_check);