PCI/ACPI: Remove unnecessary _OSC evaluation for control request

If a control had already been granted, we don't need to re-evaluate
_OSC for it because firmware may not reject control of any feature it
has previously granted control to.

Reviewed-by: Andrew Patterson <andrew.patterson@hp.com>
Tested-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index c580a525d9ce..736bb248008e 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -210,6 +210,10 @@ acpi_status pci_osc_control_set(acpi_handle handle, u32 flags)
                 goto out;
         }
 
+        /* No need to evaluate _OSC if the control was already granted. */
+        if ((osc_data->control_set & ctrlset) == ctrlset)
+                goto out;
+
         if (!osc_data->is_queried) {
                 status = __acpi_query_osc(osc_data->support_set, osc_data);
                 if (ACPI_FAILURE(status))