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This leads the link's L1.2 between PCIe Root Port and child device gets wrong configs when a caller tries to enabled it. Here is a failed example on ASUS B1400CEAE with enabled VMD: 10000:e0:06.0 PCI bridge: Intel Corporation 11th Gen Core Processor PCIe Controller (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_Substates+ PortCommonModeRestoreTime=45us PortTPowerOnTime=50us L1SubCtl1: PCI-PM_L1.2- PCI-PM_L1.1- ASPM_L1.2+ ASPM_L1.1- T_CommonMode=45us LTR1.2_Threshold=101376ns L1SubCtl2: T_PwrOn=50us 10000:e1:00.0 Non-Volatile memory controller: Sandisk Corp WD Blue SN550 NVMe SSD (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_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=0ns L1SubCtl2: T_PwrOn=10us According to "PCIe r6.0, sec 5.5.4", before enabling ASPM L1.2 on the PCIe Root Port and the child NVMe, they should be programmed with the same LTR1.2_Threshold value. However, they have different values in this case. Invoke aspm_calc_l12_info() to program the L1.2 parameters properly before enable L1.2 bits of L1 PM Substates Control Register in __pci_enable_link_state(). Link: https://bugzilla.kernel.org/show_bug.cgi?id=218394 Signed-off-by: Jian-Hong Pan --- v2: - Prepare the PCIe LTR parameters before enable L1 Substates v3: - Only enable supported features for the L1 Substates part v4: - Focus on fixing L1.2 parameters, instead of re-initializing whole L1SS v5: - Fix typo and commit message - Split introducing aspm_get_l1ss_cap() to "PCI/ASPM: Introduce aspm_get_l1ss_cap()" drivers/pci/pcie/aspm.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index c55ac11faa73..553327dee991 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1402,6 +1402,8 @@ EXPORT_SYMBOL(pci_disable_link_state); static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) { struct pcie_link_state *link = pcie_aspm_get_link(pdev); + struct pci_dev *child = link->downstream, *parent = link->pdev; + u32 parent_l1ss_cap, child_l1ss_cap; if (!link) return -EINVAL; @@ -1433,6 +1435,16 @@ static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) link->aspm_default |= ASPM_STATE_L1_1_PCIPM | ASPM_STATE_L1; if (state & PCIE_LINK_STATE_L1_2_PCIPM) link->aspm_default |= ASPM_STATE_L1_2_PCIPM | ASPM_STATE_L1; + /* + * Ensure L1.2 parameters: Common_Mode_Restore_Times, T_POWER_ON and + * LTR_L1.2_THRESHOLD are programmed properly before enable bits for + * L1.2, per PCIe r6.0, sec 5.5.4. + */ + if (state & link->aspm_capable & ASPM_STATE_L1_2_MASK) { + parent_l1ss_cap = aspm_get_l1ss_cap(parent); + child_l1ss_cap = aspm_get_l1ss_cap(child); + aspm_calc_l12_info(link, parent_l1ss_cap, child_l1ss_cap); + } pcie_config_aspm_link(link, policy_to_aspm_state(link)); link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0;