Re: [PATCH 0/2] PCI: Clean up match_driver flag usage

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Apr 25, 2025 at 11:24:20AM +0200, Lukas Wunner wrote:
> 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(-)

Provisionally applied to pci/enumeration for build testing, pending
ack from AMD IOMMU folks.