linux/drivers/acpi/pci_root.c, branch v2.6.39-rc2

PCI: Disable ASPM when _OSC control is not granted for PCIe services

2011-03-21T16:41:08Z

v3 -> v2: Added text to describe the problem v2 -> v1: Split this patch from v1 v1 : Part of: http://marc.info/?l=linux-pci&m=130042212003242&w=2 Disable ASPM when no _OSC control for PCIe services is granted by the BIOS. This is to protect systems with a buggy BIOS that did not set the ACPI FADT "ASPM Controls" bit even though the underlying HW can't do ASPM. To turn "on" ASPM the minimum the BIOS needs to do: 1. Clear the ACPI FADT "ASPM Controls" bit. 2. Support _OSC appropriately There is no _OSC Control bit for ASPM. However, we expect the BIOS to support _OSC for a Root Bridge that originates a PCIe hierarchy. If this is not the case - we are better off not enabling ASPM on that server. Commit 852972acff8f10f3a15679be2059bb94916cba5d (ACPI: Disable ASPM if the Platform won't provide _OSC control for PCIe) describes the above scenario. To quote verbatim from there: [The PCI SIG documentation for the _OSC OS/firmware handshaking interface states: "If the _OSC control method is absent from the scope of a host bridge device, then the operating system must not enable or attempt to use any features defined in this section for the hierarchy originated by the host bridge." The obvious interpretation of this is that the OS should not attempt to use PCIe hotplug, PME or AER - however, the specification also notes that an _OSC method is *required* for PCIe hierarchies, and experimental validation with An Alternative OS indicates that it doesn't use any PCIe functionality if the _OSC method is missing. That arguably means we shouldn't be using MSI or extended config space, but right now our problems seem to be limited to vendors being surprised when ASPM gets enabled on machines when other OSs refuse to do so. So, for now, let's just disable ASPM if the _OSC method doesn't exist or refuses to hand over PCIe capability control.] Signed-off-by: Naga Chumbalkar Cc: Rafael J. Wysocki Cc: Matthew Garrett Signed-off-by: Jesse Barnes

PCI/ACPI: Report ASPM support to BIOS if not disabled from command line

2011-03-21T16:38:02Z

We need to distinguish the situation in which ASPM support is disabled from the command line or through .config from the situation in which it is disabled, because the hardware or BIOS can't handle it. In the former case we should not report ASPM support to the BIOS through ACPI _OSC, but in the latter case we should do that. Introduce pcie_aspm_support_enabled() that can be used by acpi_pci_root_add() to determine whether or not it should report ASPM support to the BIOS through _OSC. Cc: stable@kernel.org References: https://bugzilla.kernel.org/show_bug.cgi?id=29722 References: https://bugzilla.kernel.org/show_bug.cgi?id=20232 Reported-and-tested-by: Ortwin Glück Reviewed-by: Kenji Kaneshige Tested-by: Kenji Kaneshige Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes

ACPI: Fix boot problem related to APEI with acpi_disabled set

2011-01-16T19:56:26Z

Commit 415e12b23792 ("PCI/ACPI: Request _OSC control once for each root bridge (v3)") put the acpi_hest_init() call in acpi_pci_root_init() into a wrong place, presumably because the author confused acpi_pci_disabled with acpi_disabled. Bring the code ordering in acpi_pci_root_init() back to sanity. Additionally, make sure that hest_disable is set when acpi_disabled is set, which is going to prevent acpi_hest_parse(), that still may be executed for acpi_disabled=1 through aer_acpi_firmware_first(), from crashing because of uninitialized hest_tab. Reported-and-tested-by: Andres Salomon Signed-off-by: Rafael J. Wysocki Signed-off-by: Linus Torvalds

PCI/ACPI: Request _OSC control once for each root bridge (v3)

2011-01-14T16:55:41Z

Move the evaluation of acpi_pci_osc_control_set() (to request control of PCI Express native features) into acpi_pci_root_add() to avoid calling it many times for the same root complex with the same arguments. Additionally, check if all of the requisite _OSC support bits are set before calling acpi_pci_osc_control_set() for a given root complex. References: https://bugzilla.kernel.org/show_bug.cgi?id=20232 Reported-by: Ozan Caglayan Tested-by: Ozan Caglayan Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes

ACPI: remove unused declaration of proc_fs.h

2010-10-16T02:03:36Z

Remove unused declaration of proc_fs.h. Signed-off-by: Zhang Rui Signed-off-by: Len Brown

PCI: PCIe: Ask BIOS for control of all native services at once

2010-08-24T20:47:33Z

After commit 852972acff8f10f3a15679be2059bb94916cba5d (ACPI: Disable ASPM if the platform won't provide _OSC control for PCIe) control of the PCIe Capability Structure is unconditionally requested by acpi_pci_root_add(), which in principle may cause problems to happen in two ways. First, the BIOS may refuse to give control of the PCIe Capability Structure if it is not asked for any of the _OSC features depending on it at the same time. Second, the BIOS may assume that control of the _OSC features depending on the PCIe Capability Structure will be requested in the future and may behave incorrectly if that doesn't happen. For this reason, control of the PCIe Capability Structure should always be requested along with control of any other _OSC features that may depend on it (ie. PCIe native PME, PCIe native hot-plug, PCIe AER). Rework the PCIe port driver so that (1) it checks which native PCIe port services can be enabled, according to the BIOS, and (2) it requests control of all these services simultaneously. In particular, this causes pcie_portdrv_probe() to fail if the BIOS refuses to grant control of the PCIe Capability Structure, which means that no native PCIe port services can be enabled for the PCIe Root Complex the given port belongs to. If that happens, ASPM is disabled to avoid problems with mishandling it by the part of the PCIe hierarchy for which control of the PCIe Capability Structure has not been received. Make it possible to override this behavior using 'pcie_ports=native' (use the PCIe native services regardless of the BIOS response to the control request), or 'pcie_ports=compat' (do not use the PCIe native services at all). Accordingly, rework the existing PCIe port service drivers so that they don't request control of the services directly. Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes

ACPI/PCI: Negotiate _OSC control bits before requesting them

2010-08-24T20:44:40Z

It is possible that the BIOS will not grant control of all _OSC features requested via acpi_pci_osc_control_set(), so it is recommended to negotiate the final set of _OSC features with the query flag set before calling _OSC to request control of these features. To implement it, rework acpi_pci_osc_control_set() so that the caller can specify the mask of _OSC control bits to negotiate and the mask of _OSC control bits that are absolutely necessary to it. Then, acpi_pci_osc_control_set() will run _OSC queries in a loop until the mask of _OSC control bits returned by the BIOS is equal to the mask passed to it. Also, before running the _OSC request acpi_pci_osc_control_set() will check if the caller's required control bits are present in the final mask. Using this mechanism we will be able to avoid situations in which the BIOS doesn't grant control of certain _OSC features, because they depend on some other _OSC features that have not been requested. Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes

ACPI/PCI: Do not preserve _OSC control bits returned by a query

2010-08-24T20:44:17Z

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 Signed-off-by: Jesse Barnes

ACPI/PCI: Make acpi_pci_query_osc() return control bits

2010-08-24T20:43:24Z

Make acpi_pci_query_osc() use an additional pointer argument to return the mask of control bits obtained from the BIOS to the caller. Signed-off-by: Rafael J. Wysocki Signed-off-by: Jesse Barnes

ACPI/PCI: Reorder checks in acpi_pci_osc_control_set()

2010-08-24T20:43:20Z

Make acpi_pci_osc_control_set() attempt to find the handle of the _OSC object under the given PCI root bridge object after verifying that its second argument is correct and that there is a struct acpi_pci_root object for the given root bridge handle, which is more logical than the old code. Signed-off-by: Rafael J. Wysocki Reviewed-by: Hidetoshi Seto Signed-off-by: Jesse Barnes