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authorRafael J. Wysocki <rjw@sisk.pl>2010-08-21 22:02:38 +0200
committerJesse Barnes <jbarnes@virtuousgeek.org>2010-08-24 13:47:33 -0700
commit28eb5f274a305bf3a13b2c80c4804d4515d05c64 (patch)
treec878c8a90a8f8e59b90460eb2f47bbbddfbd5483 /Documentation
parent75fb60f26befb59dbfa05cb122972642b7bdd219 (diff)
downloadlinux-linaro-android-28eb5f274a305bf3a13b2c80c4804d4515d05c64.tar.gz
PCI: PCIe: Ask BIOS for control of all native services at once
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 <rjw@sisk.pl> Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/kernel-parameters.txt13
1 files changed, 6 insertions, 7 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index b9008fc3a53..8f126e878db 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2043,18 +2043,17 @@ and is between 256 and 4096 characters. It is defined in the file
WARNING: Forcing ASPM on may cause system lockups.
pcie_ports= [PCIE] PCIe ports handling:
+ auto Ask the BIOS whether or not to use native PCIe services
+ associated with PCIe ports (PME, hot-plug, AER). Use
+ them only if that is allowed by the BIOS.
+ native Use native PCIe services associated with PCIe ports
+ unconditionally.
compat Treat PCIe ports as PCI-to-PCI bridges, disable the PCIe
ports driver.
pcie_pme= [PCIE,PM] Native PCIe PME signaling options:
- Format: {auto|force}[,nomsi]
- auto Use native PCIe PME signaling if the BIOS allows the
- kernel to control PCIe config registers of root ports.
- force Use native PCIe PME signaling even if the BIOS refuses
- to allow the kernel to control the relevant PCIe config
- registers.
nomsi Do not use MSI for native PCIe PME signaling (this makes
- all PCIe root ports use INTx for everything).
+ all PCIe root ports use INTx for all services).
pcmv= [HW,PCMCIA] BadgePAD 4