From a2b7b01c072435b7832ab392167545a1b38cabc3 Mon Sep 17 00:00:00 2001
From: Len Brown <len.brown@intel.com>
Date: Wed, 28 Jan 2009 12:47:15 -0500
Subject: [PATCH] ACPI: remove locking from PM1x_STS register reads
PM1a_STS and PM1b_STS are twins that get OR'd together
on reads, and all writes are repeated to both.
The fields in PM1x_STS are single bits only,
there are no multi-bit fields.
So it is not necessary to lock PM1x_STS reads against
writes because it is impossible to read an intermediate
value of a single bit. It will either be 0 or 1,
even if a write is in progress during the read.
Reads are asynchronous to writes no matter if a lock
is used or not.
Signed-off-by: Len Brown <len.brown@intel.com>
---
drivers/acpi/processor_idle.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 66a9d81455628..ae0010821ce36 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -447,7 +447,7 @@ static void acpi_processor_idle(void)
pr->power.bm_activity <<= diff;
- acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
+ acpi_get_register_unlocked(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
if (bm_status) {
pr->power.bm_activity |= 0x1;
acpi_set_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
@@ -1383,7 +1383,7 @@ static int acpi_idle_bm_check(void)
{
u32 bm_status = 0;
- acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
+ acpi_get_register_unlocked(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
if (bm_status)
acpi_set_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
/*
--
2.30.2