ACPICA: GPE detect optimization - ignore unused GPE registers

This optimization will simply ignore GPE registers that contain
no enabled GPEs - there is no need to read the register.
ACPICA bugzilla 884.

http://www.acpica.org/bugzilla/show_bug.cgi?id=884

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/evgpe.c b/drivers/acpi/acpica/evgpe.c
index 14988a86066f..67d44ef2fbc1 100644
--- a/drivers/acpi/acpica/evgpe.c
+++ b/drivers/acpi/acpica/evgpe.c
@@ -373,6 +373,15 @@ u32 acpi_ev_gpe_detect(struct acpi_gpe_xrupt_info * gpe_xrupt_list)
 
                         gpe_register_info = &gpe_block->register_info[i];
 
+                        /*
+                         * Optimization: If there are no GPEs enabled within this
+                         * register, we can safely ignore the entire register.
+                         */
+                        if (!(gpe_register_info->enable_for_run |
+                              gpe_register_info->enable_for_wake)) {
+                                continue;
+                        }
+
                         /* Read the Status Register */
 
                         status =