[PATCH 2/6] ACPI/PCI: do not preserve query result

[Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>]

Currently, all the _OSC controls are queried at the same time in
acpi_pci_osc_support() and the result is preserved for later
acpi_pci_osc_control_set() call. But query result can vary depending
on the combination of requested controls. Therefore, query result must
not be preserved.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>

---
 drivers/acpi/pci_root.c |   49 ++++++++++++++++++++++++++----------------------
 include/acpi/acpi_bus.h |    3 --
 2 files changed, 27 insertions(+), 25 deletions(-)

Index: linux-2.6.35-rc6/drivers/acpi/pci_root.c
===================================================================
--- linux-2.6.35-rc6.orig/drivers/acpi/pci_root.c
+++ linux-2.6.35-rc6/drivers/acpi/pci_root.c
@@ -230,35 +230,42 @@ static acpi_status acpi_pci_run_osc(acpi
 	return status;
 }
 
-static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root, u32 flags)
+static acpi_status acpi_pci_osc_control_query(struct acpi_pci_root *root,
+					      u32 flags, u32 *result)
 {
-	acpi_status status;
-	u32 result;
-
-	/* do _OSC query for all possible controls */
-	flags &= OSC_PCI_SUPPORT_MASKS;
-	status = acpi_pci_run_osc(root->device->handle,
-				  root->osc_support_set | flags,
-				  OSC_PCI_CONTROL_MASKS,
-				  true, &result);
-	if (ACPI_SUCCESS(status)) {
-		root->osc_support_set |= flags;
-		root->osc_control_qry = result;
-		root->osc_queried = 1;
+	/* No need to run _OSC if requested control bits are already granted */
+	flags &= OSC_PCI_CONTROL_MASKS;
+	if ((root->osc_control_set & flags) == flags) {
+		*result = root->osc_control_set;
+		return AE_OK;
 	}
-	return status;
+	return acpi_pci_run_osc(root->device->handle,
+				root->osc_support_set,
+				root->osc_control_set | flags,
+				true, result);
 }
 
 static acpi_status acpi_pci_osc_support(struct acpi_pci_root *root, u32 flags)
 {
 	acpi_status status;
 	acpi_handle tmp;
+	u32 result;
 
 	status = acpi_get_handle(root->device->handle, "_OSC", &tmp);
 	if (ACPI_FAILURE(status))
 		return status;
 	mutex_lock(&osc_lock);
-	status = acpi_pci_query_osc(root, flags);
+	/* No need to run _OSC if requested support bits are already set */
+	flags &= OSC_PCI_SUPPORT_MASKS;
+	if ((root->osc_support_set & flags) == flags)
+		goto out;
+	status = acpi_pci_run_osc(root->device->handle,
+				  root->osc_support_set | flags,
+				  root->osc_control_set,
+				  true, &result);
+	if (ACPI_SUCCESS(status))
+		root->osc_support_set |= flags;
+out:
 	mutex_unlock(&osc_lock);
 	return status;
 }
@@ -399,12 +406,10 @@ acpi_status acpi_pci_osc_control_set(acp
 		goto out;
 
 	/* Need to query controls first before requesting them */
-	if (!root->osc_queried) {
-		status = acpi_pci_query_osc(root, root->osc_support_set);
-		if (ACPI_FAILURE(status))
-			goto out;
-	}
-	if ((root->osc_control_qry & control_req) != control_req) {
+	status = acpi_pci_osc_control_query(root, control_req, &result);
+	if (ACPI_FAILURE(status))
+		goto out;
+	if ((result & control_req) != control_req) {
 		printk(KERN_DEBUG
 		       "Firmware did not grant requested _OSC control\n");
 		status = AE_SUPPORT;
Index: linux-2.6.35-rc6/include/acpi/acpi_bus.h
===================================================================
--- linux-2.6.35-rc6.orig/include/acpi/acpi_bus.h
+++ linux-2.6.35-rc6/include/acpi/acpi_bus.h
@@ -377,9 +377,6 @@ struct acpi_pci_root {
 
 	u32 osc_support_set;	/* _OSC state of support bits */
 	u32 osc_control_set;	/* _OSC state of control bits */
-	u32 osc_control_qry;	/* the latest _OSC query result */
-
-	u32 osc_queried:1;	/* has _OSC control been queried? */
 };
 
 /* helper */