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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/acpi.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/acpi.h')
| -rw-r--r-- | include/linux/acpi.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 15bfb15c2fa5..49f63c67a9d1 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -506,7 +506,8 @@ extern bool osc_pc_lpi_support_confirmed; #define OSC_PCI_EXPRESS_PME_CONTROL 0x00000004 #define OSC_PCI_EXPRESS_AER_CONTROL 0x00000008 #define OSC_PCI_EXPRESS_CAPABILITY_CONTROL 0x00000010 -#define OSC_PCI_CONTROL_MASKS 0x0000001f +#define OSC_PCI_EXPRESS_LTR_CONTROL 0x00000020 +#define OSC_PCI_CONTROL_MASKS 0x0000003f #define ACPI_GSB_ACCESS_ATTRIB_QUICK 0x00000002 #define ACPI_GSB_ACCESS_ATTRIB_SEND_RCV 0x00000004 |