ACPI: suspend: restore BM_RLD on resume

In 2.6.29,
31878dd8
"ACPI: remove BM_RLD access from idle entry path"
moved BM_RLD initialization to init-time from run time.

But we discovered that some BIOS do not restore BM_RLD
after suspend, causing device errors on C3 and C4
after resume.  So now the kernel restores BM_RLD.

http://bugzilla.kernel.org/show_bug.cgi?id=13032Signed-off-by: NLen Brown <len.brown@intel.com>

drivers/acpi/processor_idle.c

@@ -202,15 +202,38 @@ static void acpi_state_timer_broadcast(struct acpi_processor *pr,
  * Suspend / resume control
  */
 static int acpi_idle_suspend;
+static u32 saved_bm_rld;
+
+static void acpi_idle_bm_rld_save(void)
+{
+	acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &saved_bm_rld);
+}
+static void acpi_idle_bm_rld_restore(void)
+{
+	u32 resumed_bm_rld;
+
+	acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &resumed_bm_rld);
+
+	if (resumed_bm_rld != saved_bm_rld)
+		acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, saved_bm_rld);
+}
 
 int acpi_processor_suspend(struct acpi_device * device, pm_message_t state)
 {
+	if (acpi_idle_suspend == 1)
+		return 0;
+
+	acpi_idle_bm_rld_save();
 	acpi_idle_suspend = 1;
 	return 0;
 }
 
 int acpi_processor_resume(struct acpi_device * device)
 {
+	if (acpi_idle_suspend == 0)
+		return 0;
+
+	acpi_idle_bm_rld_restore();
 	acpi_idle_suspend = 0;
 	return 0;
 }