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From: Lukas Wunner <lukas@wunner.de>
To: Bjorn Helgaas <helgaas@kernel.org>,
	Joerg Roedel <joro@8bytes.org>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: linux-pci@vger.kernel.org, iommu@lists.linux.dev,
	Borislav Petkov <bp@alien8.de>
Subject: [PATCH 0/2] PCI: Clean up match_driver flag usage
Date: Fri, 25 Apr 2025 11:24:20 +0200	[thread overview]
Message-ID: <cover.1745572340.git.lukas@wunner.de> (raw)

A small puzzle piece to improve maintainability of the PCI core:

The match_driver flag in struct pci_dev is used to postpone driver
binding until all PCI devices have been enumerated.

The AMD IOMMU driver fiddles with the flag to work around breakage
introduced 10 years ago.  The breaking change has since been reverted,
so accessing the flag appears to be superfluous and is hereby dropped
(patch [1/2]).  The patch needs an ack from AMD IOMMU maintainers.

This clears the way for moving the flag to struct pci_dev's priv_flags
and thus prevent any further abuse outside the PCI core (patch [2/2]).

There are already two patches queued up in this cycle which amend
priv_flags with new definitions for bits 4, 5 and 6 (on the pci/hotplug
and pci/bwctrl topic branches), hence the bit number used here is 7.

Lukas Wunner (2):
  Revert "iommu/amd: Prevent binding other PCI drivers to IOMMU PCI
    devices"
  PCI: Limit visibility of match_driver flag to PCI core

 drivers/iommu/amd/init.c |  3 ---
 drivers/pci/bus.c        |  4 +++-
 drivers/pci/pci-driver.c |  2 +-
 drivers/pci/pci.h        | 11 +++++++++++
 drivers/pci/probe.c      |  1 -
 include/linux/pci.h      |  2 --
 6 files changed, 15 insertions(+), 8 deletions(-)

-- 
2.47.2


             reply	other threads:[~2025-04-25  9:25 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-04-25  9:24 Lukas Wunner [this message]
2025-04-25  9:24 ` [PATCH 1/2] Revert "iommu/amd: Prevent binding other PCI drivers to IOMMU PCI devices" Lukas Wunner
2025-05-12 13:28   ` Lukas Wunner
2025-05-13  7:08   ` Joerg Roedel
2025-04-25  9:24 ` [PATCH 2/2] PCI: Limit visibility of match_driver flag to PCI core Lukas Wunner
2025-04-25 16:32 ` [PATCH 0/2] PCI: Clean up match_driver flag usage Bjorn Helgaas

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