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But, cleared after pci_reset_bus() and have not been restored correctly. This leads the link's L1.2 between PCIe Root Port and child device gets wrong configs. Here is a failed example on ASUS B1400CEAE with enabled VMD. Both PCIe bridge and NVMe device should have the same LTR1.2_Threshold value. However, they are configured as different values in this case: 10000:e0:06.0 PCI bridge [0604]: Intel Corporation 11th Gen Core Processor = PCIe Controller [8086:9a09] (rev 01) (prog-if 00 [Normal decode]) ... Capabilities: [200 v1] L1 PM Substates L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1+ ASPM_L1.2+ ASPM_L1.1+ L1_PM_Substat= es+ PortCommonModeRestoreTime=3D45us PortTPowerOnTime=3D50us L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- T_CommonMode=3D0us LTR1.2_Threshold=3D0ns L1SubCtl2: T_PwrOn=3D0us 10000:e1:00.0 Non-Volatile memory controller [0108]: Sandisk Corp WD Blue S= N550 NVMe SSD [15b7:5009] (rev 01) (prog-if 02 [NVM Express]) ... Capabilities: [900 v1] L1 PM Substates L1SubCap: PCI-PM_L1.2+ PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- L1_PM_Substat= es+ PortCommonModeRestoreTime=3D32us PortTPowerOnTime=3D10us L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- T_CommonMode=3D0us LTR1.2_Threshold=3D101376ns L1SubCtl2: T_PwrOn=3D50us Here is VMD mapped PCI device tree: -+-[0000:00]-+-00.0 Intel Corporation Device 9a04 | ... \-[10000:e0]-+-06.0-[e1]----00.0 Sandisk Corp WD Blue SN550 NVMe SSD \-17.0 Intel Corporation Tiger Lake-LP SATA Controller When pci_reset_bus() resets the bus [e1] of the NVMe, it only saves and restores NVMe's state before and after reset. Because bus [e1] has only one device: 10000:e1:00.0 NVMe. The PCIe bridge is missed. However, when it restores the NVMe's state, it also restores the ASPM L1SS between the PCIe bridge and the NVMe by pci_restore_aspm_l1ss_state(). The NVMe's L1SS is restored correctly. But, the PCIe bridge's L1SS is restored with the wrong value 0x0 [1]. Because, the parent device (PCIe bridge)'s L1SS is not saved by pci_save_aspm_l1ss_state() before reset. That is why pci_restore_aspm_l1ss_state() gets the parent device (PCIe bridge)'s saved state capability data and restores L1SS with value 0. So, if the PCI device has a parent, make pci_save_aspm_l1ss_state() save the parent's L1SS configuration, too. This is symmetric on pci_restore_aspm_l1ss_state(). [1]: https://lore.kernel.org/linux-pci/CAPpJ_eexU0gCHMbXw_z924WxXw0+B6SdS4e= G9oGpEX1wmnMLkQ@mail.gmail.com/ Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D218394 Signed-off-by: Jian-Hong Pan Suggested-by: Ilpo J=C3=A4rvinen --- v9: - Drop the v8 fix about drivers/pci/pcie/aspm.c. Use this in VMD instead. v10: - Drop the v9 fix about drivers/pci/controller/vmd.c - Fix in PCIe ASPM to make it symmetric between pci_save_aspm_l1ss_state() and pci_restore_aspm_l1ss_state() drivers/pci/pcie/aspm.c | 39 +++++++++++++++++++++++++++++++-------- 1 file changed, 31 insertions(+), 8 deletions(-) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index bd0a8a05647e..823aaf813978 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -81,24 +81,47 @@ void pci_configure_aspm_l1ss(struct pci_dev *pdev) =20 void pci_save_aspm_l1ss_state(struct pci_dev *pdev) { - struct pci_cap_saved_state *save_state; - u16 l1ss =3D pdev->l1ss; + struct pci_cap_saved_state *pl_save_state, *cl_save_state; + struct pci_dev *parent; u32 *cap; =20 /* * Save L1 substate configuration. The ASPM L0s/L1 configuration * in PCI_EXP_LNKCTL_ASPMC is saved by pci_save_pcie_state(). */ - if (!l1ss) + if (!pdev->l1ss) return; =20 - save_state =3D pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_L1SS); - if (!save_state) + cl_save_state =3D pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_L1SS); + if (!cl_save_state) return; =20 - cap =3D &save_state->cap.data[0]; - pci_read_config_dword(pdev, l1ss + PCI_L1SS_CTL2, cap++); - pci_read_config_dword(pdev, l1ss + PCI_L1SS_CTL1, cap++); + cap =3D &cl_save_state->cap.data[0]; + pci_read_config_dword(pdev, pdev->l1ss + PCI_L1SS_CTL2, cap++); + pci_read_config_dword(pdev, pdev->l1ss + PCI_L1SS_CTL1, cap++); + + /* + * If here is a parent device and it has not saved state, save parent's + * L1 substate configuration, too. This is symmetric on + * pci_restore_aspm_l1ss_state(). + */ + if (!pdev->bus || !pdev->bus->self) + return; + + parent =3D pdev->bus->self; + if (!parent->l1ss) + return; + + pl_save_state =3D pci_find_saved_ext_cap(parent, PCI_EXT_CAP_ID_L1SS); + if (!pl_save_state) + return; + + if (parent->state_saved) + return; + + cap =3D &pl_save_state->cap.data[0]; + pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL2, cap++); + pci_read_config_dword(parent, parent->l1ss + PCI_L1SS_CTL1, cap++); } =20 void pci_restore_aspm_l1ss_state(struct pci_dev *pdev) --=20 2.46.2