ACPICA: Misc comments to minimize code divergence

Modify/add some comments to minimize ACPICA/linux GPE code divergence.

Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/drivers/acpi/acpica/evgpeinit.c b/drivers/acpi/acpica/evgpeinit.c
index 734a494bd705..c59dc2340593 100644
--- a/drivers/acpi/acpica/evgpeinit.c
+++ b/drivers/acpi/acpica/evgpeinit.c
@@ -45,11 +45,27 @@
 #include "accommon.h"
 #include "acevents.h"
 #include "acnamesp.h"
-#include "acinterp.h"
 
 #define _COMPONENT          ACPI_EVENTS
 ACPI_MODULE_NAME("evgpeinit")
 
+/*
+ * Note: History of _PRW support in ACPICA
+ *
+ * Originally (2000 - 2010), the GPE initialization code performed a walk of
+ * the entire namespace to execute the _PRW methods and detect all GPEs
+ * capable of waking the system.
+ *
+ * As of 10/2010, the _PRW method execution has been removed since it is
+ * actually unnecessary. The host OS must in fact execute all _PRW methods
+ * in order to identify the device/power-resource dependencies. We now put
+ * the onus on the host OS to identify the wake GPEs as part of this process
+ * and to inform ACPICA of these GPEs via the acpi_setup_gpe_for_wake interface. This
+ * not only reduces the complexity of the ACPICA initialization code, but in
+ * some cases (on systems with very large namespaces) it should reduce the
+ * kernel boot time as well.
+ */
+
 /*******************************************************************************
  *
  * FUNCTION:    acpi_ev_gpe_initialize
@@ -222,7 +238,7 @@ void acpi_ev_update_gpes(acpi_owner_id table_owner_id)
         acpi_status status = AE_OK;
 
         /*
-         * 2) Find any _Lxx/_Exx GPE methods that have just been loaded.
+         * Find any _Lxx/_Exx GPE methods that have just been loaded.
          *
          * Any GPEs that correspond to new _Lxx/_Exx methods are immediately
          * enabled.
@@ -235,9 +251,9 @@ void acpi_ev_update_gpes(acpi_owner_id table_owner_id)
                 return;
         }
 
+        walk_info.count = 0;
         walk_info.owner_id = table_owner_id;
         walk_info.execute_by_owner_id = TRUE;
-        walk_info.count = 0;
 
         /* Walk the interrupt level descriptor list */
 
@@ -298,7 +314,7 @@ void acpi_ev_update_gpes(acpi_owner_id table_owner_id)
  *                  xx     - is the GPE number [in HEX]
  *
  * If walk_info->execute_by_owner_id is TRUE, we only execute examine GPE methods
- *    with that owner.
+ * with that owner.
  *
  ******************************************************************************/