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| author |   Bjorn Helgaas <bhelgaas@google.com> | 2018-04-17 10:58:09 -0500 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2018-04-23 08:18:44 -0500 |
| commit | af8bb9f89838249872240f258e67774ccbcc5970 (patch) | |
| tree | f6f8ae73b8afe586066604ec5228ca99b4bde1af /include/linux/pci.h | |
| parent | PCI/ASPM: Disable ASPM L1.2 Substate if we don't have LTR (diff) | |
| download | linux-dev-af8bb9f89838249872240f258e67774ccbcc5970.tar.xz linux-dev-af8bb9f89838249872240f258e67774ccbcc5970.zip | |
PCI/ACPI: Request LTR control from platform before using it
Per the PCI Firmware spec r3.2, sec 4.5, an ACPI-based OS should use _OSC
to request control of Latency Tolerance Reporting (LTR) before using it.
Request control of LTR, and if the platform does not grant control, don't
use it.
N.B. If the hardware supports LTR and the ASPM L1.2 substate but the BIOS
doesn't support LTR in _OSC, we previously would enable ASPM L1.2. This
patch will prevent us from enabling ASPM L1.2 in that case. It does not
prevent us from enabling PCI-PM L1.2, since that doesn't depend on LTR.
See PCIe r40, sec 5.5.1, for the L1 PM substate entry conditions.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'include/linux/pci.h')
| -rw-r--r-- | include/linux/pci.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/pci.h b/include/linux/pci.h index 73178a2fcee0..d0149c01996d 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -473,6 +473,7 @@ struct pci_host_bridge { unsigned int native_aer:1; /* OS may use PCIe AER */ unsigned int native_hotplug:1; /* OS may use PCIe hotplug */ unsigned int native_pme:1; /* OS may use PCIe PME */ + unsigned int native_ltr:1; /* OS may use PCIe LTR */ /* Resource alignment requirements */ resource_size_t (*align_resource)(struct pci_dev *dev, const struct resource *res, |