diff options
| author | Bjorn Helgaas <bhelgaas@google.com> | 2018-04-17 19:25:51 +0300 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2018-04-19 00:10:34 +0300 |
| commit | 9ab105deb60fa76d66cae5548819b4e8703d2056 (patch) | |
| tree | 95102cdf7aa3b3922c740b535a1286ef51376c82 | |
| parent | 60cc43fc888428bb2f18f08997432d426a243338 (diff) | |
| download | linux-9ab105deb60fa76d66cae5548819b4e8703d2056.tar.xz | |
PCI/ASPM: Disable ASPM L1.2 Substate if we don't have LTR
When in the ASPM L1.0 state (but not the PCI-PM L1.0 state), the most
recent LTR value and the LTR_L1.2_THRESHOLD determines whether the link
enters the L1.2 substate.
If we don't have LTR enabled, prevent the use of ASPM L1.2.
PCI-PM L1.2 may still be used because it doesn't depend on
LTR_L1.2_THRESHOLD (see PCIe r4.0, sec 5.5.1).
Tested-by: Srinath Mannam <srinath.mannam@broadcom.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/pci/pcie/aspm.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index f76eb7704f64..c687c817b47d 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -400,6 +400,15 @@ static void pcie_get_aspm_reg(struct pci_dev *pdev, info->l1ss_cap = 0; return; } + + /* + * If we don't have LTR for the entire path from the Root Complex + * to this device, we can't use ASPM L1.2 because it relies on the + * LTR_L1.2_THRESHOLD. See PCIe r4.0, secs 5.5.4, 6.18. + */ + if (!pdev->ltr_path) + info->l1ss_cap &= ~PCI_L1SS_CAP_ASPM_L1_2; + pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL1, &info->l1ss_ctl1); pci_read_config_dword(pdev, info->l1ss_cap_ptr + PCI_L1SS_CTL2, |