Re: [PATCH v2 0/4] PCI/ASPM: Allow quirks to avoid L0s and L1

[Bjorn Helgaas <helgaas@kernel.org>]

On Mon, Nov 10, 2025 at 04:22:24PM -0600, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
> 
> 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.
> 
> 
> Bjorn Helgaas (4):
>   PCI/ASPM: Cache L0s/L1 Supported so advertised link states can be
>     overridden
>   PCI/ASPM: Add pcie_aspm_remove_cap() to override advertised link
>     states
>   PCI/ASPM: Convert quirks to override advertised link states
>   PCI/ASPM: Avoid L0s and L1 on Freescale Root Ports
> 
>  drivers/pci/pci.h       |  2 ++
>  drivers/pci/pcie/aspm.c | 25 +++++++++++++++++--------
>  drivers/pci/probe.c     |  7 +++++++
>  drivers/pci/quirks.c    | 38 +++++++++++++++++++-------------------
>  include/linux/pci.h     |  2 ++
>  5 files changed, 47 insertions(+), 27 deletions(-)

Applied to pci/for-linus, hoping for v6.18.  Thanks Shawn and Lukas
for testing and reviewing.  Any other comments and testing would be
very welcome.

I think we'll need to add a similar quirk for Christian's X1000
([🔎] a41d2ca1-fcd9-c416-b111-a958e92e94bf@xenosoft.de">https://lore.kernel.org/r/[🔎] a41d2ca1-fcd9-c416-b111-a958e92e94bf@xenosoft.de),
but I don't know the device ID for it yet.

> -- 
> 
> v1: [🔎] 20251106183643.1963801-1-helgaas@kernel.org">https://lore.kernel.org/r/[🔎] 20251106183643.1963801-1-helgaas@kernel.org
> 
> Changes between v1 and v2:
> - Cache just the two bits for L0s and L1 support, not the entire Link
>   Capabilities (Lukas)
> - Add pcie_aspm_remove_cap() to override the ASPM Support bits in Link
>   Capabilities (Lukas)
> - Convert existing quirks to use pcie_aspm_remove_cap() instead of
>   pci_disable_link_state(), and from FINAL to HEADER (Mani)