linux-kernel - [PATCH v3 00/10] PCI/PM: Always disable PTM for all devices during suspend

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Message-Id: <20220906222351.64760-1-helgaas@kernel.org>
Date:   Tue,  6 Sep 2022 17:23:41 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Rajvi Jingar <rajvi.jingar@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael@...nel.org>
Cc:     Koba Ko <koba.ko@...onical.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "David E . Box" <david.e.box@...ux.intel.com>,
        Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        linux-pci@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v3 00/10] PCI/PM: Always disable PTM for all devices during suspend

From: Bjorn Helgaas <bhelgaas@...gle.com>

We currently disable PTM for Root Ports during suspend.  Leaving PTM
enabled for downstream devices causes UR errors if they send PTM Requests.
The intent of this series is to:

  - Unconditionally disable PTM during suspend (even if the driver saves
    its own state) by moving the disable from pci_prepare_to_sleep() to
    pci_pm_suspend().

  - Disable PTM for all devices by removing the Root Port condition and
    doing it early in the suspend paths.

  - Explicitly re-enable PTM during resume.

This got long and pretty complicated to read via the patches.  The end
result of ptm.c might help as a roadmap to where I hoped to go:

  https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/tree/drivers/pci/pcie/ptm.c?h=07c2204ab0f3

Basically I wanted to make pci_enable_ptm() and pci_disable_ptm() flip the
PCI_PTM_CTRL_ENABLE bit and nothing else, with all the setup based on the
PTM Capabilities register done in pci_ptm_init().

Bjorn Helgaas (10):
  PCI/PTM: Preserve PTM Root Select
  PCI/PTM: Cache PTM Capability offset
  PCI/PTM: Add pci_upstream_ptm() helper
  PCI/PTM: Separate configuration and enable
  PCI/PTM: Add pci_disable_ptm() wrapper
  PCI/PTM: Add pci_enable_ptm() wrapper
  PCI/PTM: Add suspend/resume
  PCI/PTM: Move pci_ptm_info() body into its only caller
  PCI/PTM: Reorder functions in logical order
  PCI/PM: Always disable PTM for all devices during suspend

 drivers/pci/pci-driver.c |  11 ++
 drivers/pci/pci.c        |  28 +---
 drivers/pci/pci.h        |   6 +-
 drivers/pci/pcie/ptm.c   | 317 ++++++++++++++++++++-------------------
 include/linux/pci.h      |   3 +
 5 files changed, 181 insertions(+), 184 deletions(-)

-- 
2.25.1