From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: [PATCH 5/10] ACPI / PCI: Do not preserve _OSC control bits returned by a query (v4) Date: Sat, 21 Aug 2010 01:54:41 +0200 Message-ID: <201008210154.41507.rjw@sisk.pl> References: <201008060303.51224.rjw@sisk.pl> <201008210149.39576.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <201008210149.39576.rjw@sisk.pl> Sender: linux-pci-owner@vger.kernel.org To: Hidetoshi Seto Cc: linux-pm@lists.linux-foundation.org, Kenji Kaneshige , linux-pci@vger.kernel.org, Jesse Barnes , ACPI Devel Maling List , Matthew Garrett List-Id: linux-acpi@vger.kernel.org From: Rafael J. Wysocki 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. For this reason, 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 --- drivers/acpi/pci_root.c | 20 +++++++------------- include/acpi/acpi_bus.h | 3 --- 2 files changed, 7 insertions(+), 16 deletions(-) Index: linux-2.6/drivers/acpi/pci_root.c =================================================================== --- linux-2.6.orig/drivers/acpi/pci_root.c +++ linux-2.6/drivers/acpi/pci_root.c @@ -249,12 +249,8 @@ static acpi_status acpi_pci_query_osc(st 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(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, 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; } Index: linux-2.6/include/acpi/acpi_bus.h =================================================================== --- linux-2.6.orig/include/acpi/acpi_bus.h +++ linux-2.6/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 */