From 2b8fd9186d9275b07aef43e5bb4e98cd571f9a7d Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <rjw@sisk.pl>
Date: Mon, 23 Aug 2010 23:55:59 +0200
Subject: [PATCH] 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>
---
drivers/acpi/pci_root.c | 20 +++++++-------------
include/acpi/acpi_bus.h | 3 ---
2 files changed, 7 insertions(+), 16 deletions(-)
diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index d2ae816df0f5..77cd19697b1e 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 baacd98e7cc6..4de84ce3a927 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 */
--
2.30.9