Commit ee1ca48f authored by Pallipadi, Venkatesh's avatar Pallipadi, Venkatesh Committed by Len Brown
Browse files

ACPI: Disable ARB_DISABLE on platforms where it is not needed



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.
Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent cd86a536
......@@ -34,12 +34,22 @@ void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
flags->bm_check = 1;
else if (c->x86_vendor == X86_VENDOR_INTEL) {
/*
* Today all CPUs that support C3 share cache.
* TBD: This needs to look at cache shared map, once
* multi-core detection patch makes to the base.
* Today all MP CPUs that support C3 share cache.
* And caches should not be flushed by software while
* entering C3 type state.
*/
flags->bm_check = 1;
}
/*
* On all recent Intel platforms, ARB_DISABLE is a nop.
* So, set bm_control to zero to indicate that ARB_DISABLE
* is not required while entering C3 type state on
* P4, Core and beyond CPUs
*/
if (c->x86_vendor == X86_VENDOR_INTEL &&
(c->x86 > 0x6 || (c->x86 == 6 && c->x86_model >= 14)))
flags->bm_control = 0;
}
EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
......
......@@ -512,7 +512,8 @@ static void acpi_processor_power_verify_c2(struct acpi_processor_cx *cx)
static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
struct acpi_processor_cx *cx)
{
static int bm_check_flag;
static int bm_check_flag = -1;
static int bm_control_flag = -1;
if (!cx->address)
......@@ -542,12 +543,14 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
}
/* All the logic here assumes flags.bm_check is same across all CPUs */
if (!bm_check_flag) {
if (bm_check_flag == -1) {
/* Determine whether bm_check is needed based on CPU */
acpi_processor_power_init_bm_check(&(pr->flags), pr->id);
bm_check_flag = pr->flags.bm_check;
bm_control_flag = pr->flags.bm_control;
} else {
pr->flags.bm_check = bm_check_flag;
pr->flags.bm_control = bm_control_flag;
}
if (pr->flags.bm_check) {
......
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