[PATCH 00/11] PCI: pci_resource_alignment() improvement + cleanups

Ilpo Järvinen
2026-04-29T12:26:28Z

pci_resource_alignment() returns 0 when resource is already assigned
and in case of disabled bridge windows. This has caused problems to
calculations relying on pci_resource_alignment():

https://lore.kernel.org/linux-pci/LV8P221MB1472A24B9975F7C8E8D6BF929947A@LV8P221MB1472.NAMP221.PROD.OUTLOOK.COM/

This series reworks pci_resource_alignment() interface to return always
non-zero alignment if the resource exists. For assigned bridge windows,
the calculation is using heuristic based on size and start address
alignment as calculating the alignment again is costly (would require
sizing the entire sub-hierarchy).

As pci_resource_alignment() is becoming more complicated, it's also
moved to setup-res.c. While moving pci_resource_alignment()'s arguments
are converted into const to tell compiler it can rely on resource
remaining the same across the call.

This was intended to be part of a larger series that addresses some
shortcomings in pci=realloc. The pci=realloc changes will recalculate
bridge window sizes considering also assigned resources which required
making these changes to pci_resource_alignment().

As this also relates to the issue linked above, I'm sending it already
now without pci=realloc changes that are still incomplete. The first
patches originate from the large pci=realloc work but seem generally
useful even if independent of the alignment improvements so I've
included them here without reorganizing the series to contain only
alignment related changes.

Ilpo Järvinen (11):
PCI: Log all resource claims
PCI: Rename added to add_list
PCI: Consolidate add_list (aka realloc_head) empty sanity checks
PCI: Remove const removal cast
resource: Make resource_alignment() input const resource
powerpc/pseries: Make pseries_get_iov_fw_value() & pnv_iov_get()
pci_dev const
PCI: Make pci_sriov_resource_alignment() pci_dev const
PCI: Convert pci_resource_alignment() input parameters to const
PCI: Move pci_resource_alignment() to setup-res.c file
PCI: Lower bound bridge windown alignment
PCI: Return valid alignment for assigned resources

arch/powerpc/include/asm/machdep.h | 2 +-
arch/powerpc/kernel/pci-common.c | 2 +-
arch/powerpc/platforms/powernv/pci-sriov.c | 4 +-
arch/powerpc/platforms/powernv/pci.h | 5 ++-
arch/powerpc/platforms/pseries/setup.c | 5 ++-
drivers/pci/iov.c | 7 +--
drivers/pci/pci.h | 24 ++++-------
drivers/pci/setup-bus.c | 50 ++++++++++++----------
drivers/pci/setup-cardbus.c | 2 +-
drivers/pci/setup-res.c | 37 ++++++++++++++++
include/linux/ioport.h | 2 +-
include/linux/pci.h | 8 ++--
kernel/resource.c | 2 +-
13 files changed, 94 insertions(+), 56 deletions(-)

base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
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2.39.5