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| author | Jian-Hong Pan <jhp@endlessos.org> | 2024-10-01 10:34:38 +0200 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2024-11-06 23:32:26 +0100 |
| commit | d66041063192497a4a97d21dbf86b79a03a7f4fb (patch) | |
| tree | 3d47b1a5dc4d1848ab5cd1e9d38d2e3cfed55a5c /drivers/pci/controller/vmd.c | |
| parent | PCI/ASPM: Add notes about enabling PCI-PM L1SS to pci_enable_link_state(_locked) (diff) | |
| download | linux-d66041063192497a4a97d21dbf86b79a03a7f4fb.tar.xz linux-d66041063192497a4a97d21dbf86b79a03a7f4fb.zip | |
PCI: vmd: Set devices to D0 before enabling PM L1 Substates
The remapped PCIe Root Port and the child device have PM L1 Substates
capability, but they are disabled originally.
Here is a failed example on ASUS B1400CEAE:
Capabilities: [900 v1] L1 PM Substates
L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- L1_PM_Substates+
PortCommonModeRestoreTime=32us PortTPowerOnTime=10us
L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1-
T_CommonMode=0us LTR1.2_Threshold=101376ns
L1SubCtl2: T_PwrOn=50us
Enable PCI-PM L1 PM Substates for devices below VMD while they are in D0
(see PCIe r6.0, sec 5.5.4).
Link: https://lore.kernel.org/r/20241001083438.10070-4-jhp@endlessos.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=218394
Signed-off-by: Jian-Hong Pan <jhp@endlessos.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Diffstat (limited to '')
| -rw-r--r-- | drivers/pci/controller/vmd.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c index 264a180403a0..11870d1fc818 100644 --- a/drivers/pci/controller/vmd.c +++ b/drivers/pci/controller/vmd.c @@ -740,11 +740,9 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata) if (!(features & VMD_FEAT_BIOS_PM_QUIRK)) return 0; - pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL); - pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_LTR); if (!pos) - return 0; + goto out_state_change; /* * Skip if the max snoop LTR is non-zero, indicating BIOS has set it @@ -752,7 +750,7 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata) */ pci_read_config_dword(pdev, pos + PCI_LTR_MAX_SNOOP_LAT, <r_reg); if (!!(ltr_reg & (PCI_LTR_VALUE_MASK | PCI_LTR_SCALE_MASK))) - return 0; + goto out_state_change; /* * Set the default values to the maximum required by the platform to @@ -764,6 +762,13 @@ static int vmd_pm_enable_quirk(struct pci_dev *pdev, void *userdata) pci_write_config_dword(pdev, pos + PCI_LTR_MAX_SNOOP_LAT, ltr_reg); pci_info(pdev, "VMD: Default LTR value set by driver\n"); +out_state_change: + /* + * Ensure devices are in D0 before enabling PCI-PM L1 PM Substates, per + * PCIe r6.0, sec 5.5.4. + */ + pci_set_power_state_locked(pdev, PCI_D0); + pci_enable_link_state_locked(pdev, PCIE_LINK_STATE_ALL); return 0; } |