diff mbox

[1/2] ACPI: remove locking from PM1x_STS register reads

Message ID alpine.LFD.2.00.0902032301170.5607@localhost.localdomain (mailing list archive)
State Accepted
Headers show

Commit Message

Len Brown Feb. 4, 2009, 4:02 a.m. UTC 
From: Len Brown <len.brown@intel.com>

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 files changed, 2 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 66a9d81..ae00108 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);
 	/*