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

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Message-ID: <20251110222929.2140564-1-helgaas@kernel.org>
Date: Mon, 10 Nov 2025 16:22:24 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: linux-pci@...r.kernel.org
Cc: Christian Zigotzky <chzigotzky@...osoft.de>,
	Manivannan Sadhasivam <mani@...nel.org>,
	mad skateman <madskateman@...il.com>,
	"R . T . Dickinson" <rtd2@...a.co.nz>,
	Darren Stevens <darren@...vens-zone.net>,
	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
	Lukas Wunner <lukas@...ner.de>,
	luigi burdo <intermediadc@...mail.com>,
	Al <al@...azap.net>,
	Roland <rol7and@....com>,
	Hongxing Zhu <hongxing.zhu@....com>,
	hypexed@...oo.com.au,
	linuxppc-dev@...ts.ozlabs.org,
	debian-powerpc@...ts.debian.org,
	linux-kernel@...r.kernel.org,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v2 0/4] PCI/ASPM: Allow quirks to avoid L0s and L1

From: Bjorn Helgaas <bhelgaas@...gle.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(-)

-- 

v1: 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)