@@ -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;
}
The remapped PCIe Root Port and the child device have PCI 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 Power on all of the VMD remapped PCI devices to D0 before enable PCI-PM L1 PM Substates by following "PCIe r6.0, sec 5.5.4". Link: https://bugzilla.kernel.org/show_bug.cgi?id=218394 Signed-off-by: Jian-Hong Pan <jhp@endlessos.org> --- v2: - Power on the VMD remapped devices with pci_set_power_state_locked() - Prepare the PCIe LTR parameters before enable L1 Substates - Add note into the comments of both pci_enable_link_state() and pci_enable_link_state_locked() for kernel-doc. - The original patch set can be split as individual patches. v3: - Re-send for the missed version information. - Split drivers/pci/pcie/aspm.c modification into following patches. - Fix the comment for enasuring the PCI devices in D0. v4: - The same v5: - Tweak the commit title and message - Change the goto label from out_enable_link_state to out_state_change v6~8: - The same v9: - Update L1 PM Substates information against kernel v6.11 in commit message drivers/pci/controller/vmd.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)