Attention is currently required from: John Zhao.

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• Patchset:

  • Patch Set #2:

    Patch Set 2:

    I'm not sure a root port without an attached endpoint should be able to enable ASPM, how can it know the device will be capable of it?

    If you remove the generic device from 0:7.x in chipset.cb it also does not enable ASPM, so this is not restoring any previous behavior and uses the generic device to force the link to do things that I don't think it should be able to if no device is present.

    In addition, PCI endpoints that exist on a root port at boot time are already handled properly so repeats things twice on root ports where there is actually a PCI endpoint attached.

     do_pci_scan_bridge for PCI: 00:1c.0
     PCI: pci_scan_bus for bus 2c
     PCI: 2c:00.0 [17a0/0000] ops
     GL9755: configure ASPM and LTR
     PCI: 2c:00.0 [17a0/9755] enabled
     GENERIC: 0.0 enabled
     Enabling Common Clock Configuration
     L1 Sub-State supported from root port 28
     L1 Sub-State Support = 0xf
     CommonModeRestoreTime = 0xff
     Power On Value = 0x1f, Power On Scale = 0x2
     ASPM: Enabled L1
     PCIe: Max_Payload_Size adjusted to 128
    -scan_bus: bus PCI: 00:1c.0 finished in 0 msecs
    +Enabling Common Clock Configuration
    +L1 Sub-State supported from root port 28
    +L1 Sub-State Support = 0xf
    +CommonModeRestoreTime = 0xff
    +Power On Value = 0x1f, Power On Scale = 0x2
    +ASPM: Enabled L1
    +PCIe: Max_Payload_Size adjusted to 128
    +scan_bus: bus PCI: 00:1c.0 finished in 8 msecs

    Kernel does not enable ASPM for TBT root ports. Kernel driver only handles ASPM enabling for attached devices.
    Bridges and buses behind the bridge are scanned at boot time. i.e for PCI 00:1c.0, its endpoint(bus->children) has path.type->DEVICE_PATH_PCI and its ASPM is enabled. 00:07.x configuration is skipped because its endpoints has path.type->DEVICE_PATH_GENERIC. If removing generic device from 00:07.x in chipset.cb, its endpoint is NULL which also causes configuration skipped and the TBT root ports ASPM are not enabled.
    This TBT root ports ASPM enabling features has been applied across various NDA and DA validations. No negative feedback.

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