diff options
authorRafael J. Wysocki <rjw@sisk.pl>2010-08-23 23:55:59 +0200
committerJesse Barnes <jbarnes@virtuousgeek.org>2010-08-24 13:44:17 -0700
commit2b8fd9186d9275b07aef43e5bb4e98cd571f9a7d (patch)
parentab8e8957a2ae21c0f036476c6db13e949be730ac (diff)
ACPI/PCI: Do not preserve _OSC control bits returned by a query
There is the assumption in acpi_pci_osc_control_set() that it is always sufficient to compare the mask of _OSC control bits to be requested with the result of an _OSC query where all of the known control bits have been checked. However, in general, that need not be the case. For example, if an _OSC feature A depends on an _OSC feature B and control of A, B plus another _OSC feature C is requested simultaneously, the BIOS may return A, B, C, while it would only return C if A and C were requested without B. That may result in passing a wrong mask of _OSC control bits to an _OSC control request, in which case the BIOS may only grant control of a subset of the requested features. Moreover, acpi_pci_run_osc() will return error code if that happens and the caller of acpi_pci_osc_control_set() will not know that it's been granted control of some _OSC features. Consequently, the system will generally not work as expected. Apart from this acpi_pci_osc_control_set() always uses the mask of _OSC control bits returned by the very first invocation of acpi_pci_query_osc(), but that is done with the second argument equal to OSC_PCI_SEGMENT_GROUPS_SUPPORT which generally happens to affect the returned _OSC control bits. For these reasons, make acpi_pci_osc_control_set() always check if control of the requested _OSC features will be granted before making the final control request. As a result, the osc_control_qry and osc_queried members of struct acpi_pci_root are not necessary any more, so drop them and remove the remaining code referring to them. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
2 files changed, 7 insertions, 16 deletions
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index d2ae816df0f..77cd19697b1 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -249,12 +249,8 @@ static acpi_status acpi_pci_query_osc(struct acpi_pci_root *root,
status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
if (ACPI_SUCCESS(status)) {
root->osc_support_set = support;
- if (control) {
+ if (control)
*control = result;
- } else {
- root->osc_control_qry = result;
- root->osc_queried = 1;
- }
return status;
@@ -409,14 +405,12 @@ acpi_status acpi_pci_osc_control_set(acpi_handle handle, u32 flags)
goto out;
/* Need to query controls first before requesting them */
- if (!root->osc_queried) {
- status = acpi_pci_query_osc(root, root->osc_support_set, NULL);
- if (ACPI_FAILURE(status))
- goto out;
- }
- if ((root->osc_control_qry & control_req) != control_req) {
- printk(KERN_DEBUG
- "Firmware did not grant requested _OSC control\n");
+ flags = control_req;
+ status = acpi_pci_query_osc(root, root->osc_support_set, &flags);
+ if (ACPI_FAILURE(status))
+ goto out;
+ if (flags != control_req) {
status = AE_SUPPORT;
goto out;
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index baacd98e7cc..4de84ce3a92 100644
--- a/include/acpi/acpi_bus.h
+++ b/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 */