On Mon, Nov 10, 2025 at 04:22:24PM -0600, Bjorn Helgaas wrote:
> We enabled ASPM too aggressively in v6.18-rc1. f3ac2ff14834 ("PCI/ASPM:
> Enable all ClockPM and ASPM states for devicetree platforms") enabled ASPM
> L0s, L1, and (if advertised) L1 PM Substates.
>
> df5192d9bb0e ("PCI/ASPM: Enable only L0s and L1 for devicetree platforms")
> (v6.18-rc3) backed off and omitted Clock PM and L1 Substates because we
> don't have good infrastructure to discover CLKREQ# support, and L1
> Substates may require device-specific configuration.
>
> L0s and L1 are generically discoverable and should not require
> device-specific support, but some devices advertise them even though they
> don't work correctly. This series is a way to add quirks avoid L0s and L1
> in this case.
Reviewed-by: Lukas Wunner <[email protected]>
I note that a number of drivers call pci_disable_link_state() or
pci_disable_link_state_locked() to disable ASPM on probe.
Can we convert (all of) these to quirks which use the new helper
introduced here?
I think that would be useful because it would disable ASPM even if
the driver isn't available and thus avoid e.g. AER messages caused
by ASPM issues.
pcie_aspm_init_link_state() also contains the following code comment:
/*
* At this stage drivers haven't had an opportunity to change the
* link policy setting. Enabling ASPM on broken hardware can cripple
* it even before the driver has had a chance to disable ASPM, so
* default to a safe level right now. If we're enabling ASPM beyond
* the BIOS's expectation, we'll do so once pci_enable_device() is
* called.
*/
If we'd mask out incorrect or non-working L0s/L1 capabilities for all
devices early during enumeration via quirks, we wouldn't have to go
through these contortions of setting up deeper ASPM states only at
device enable time.
Thanks,
Lukas
