[PATCH 6.6 131/283] PCI: Supply bridge device, not secondary bus, to read window details

Sasha Levin
2026-02-28T18:08:58Z

From: Bjorn Helgaas <bhelgaas@google.com>

[ Upstream commit 281e1f137a97dae4fe47a7d30635c5b83def790b ]

Previously we logged information about devices *below* the bridge before
logging information about the bridge itself, e.g.,

pci 0000:00:01.0: [8086:1901] type 01 class 0x060400
pci 0000:01:00.0: [10de:13b6] type 00 class 0x030200
pci 0000:01:00.0: reg 0x10: [mem 0xec000000-0xecffffff]
pci 0000:00:01.0: PCI bridge to [bus 01]
pci 0000:00:01.0: bridge window [io 0xe000-0xefff]

This is partly because the bridge windows are read in this path:

pci_scan_child_bus_extend
for (devfn = 0; devfn < 256; devfn += 8)
pci_scan_slot(bus, devfn) # scan below bridge
pcibios_fixup_bus(bus)
pci_read_bridge_bases(bus) # read bridge windows
pci_read_bridge_io(bus)

Remove the assumption that the secondary (child) pci_bus already exists by
passing in the bridge device (instead of the pci_bus) and a resource
pointer when reading bridge windows. A future change can use this to log
the bridge details before we enumerate the devices below the bridge.

No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Stable-dep-of: 9abf79c8d7b4 ("PCI/ACPI: Restrict program_hpx_type2() to AER bits")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/pci/probe.c | 21 ++++++---------------
1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index a43f9e9352e47..a91ac2faf9a90 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -344,13 +344,11 @@ static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom)
}
}

-static void pci_read_bridge_io(struct pci_bus *child)
+static void pci_read_bridge_io(struct pci_dev *dev, struct resource *res)
{
- struct pci_dev *dev = child->self;
u8 io_base_lo, io_limit_lo;
unsigned long io_mask, io_granularity, base, limit;
struct pci_bus_region region;
- struct resource *res;

io_mask = PCI_IO_RANGE_MASK;
io_granularity = 0x1000;
@@ -360,7 +358,6 @@ static void pci_read_bridge_io(struct pci_bus *child)
io_granularity = 0x400;
}

- res = child->resource[0];
pci_read_config_byte(dev, PCI_IO_BASE, &io_base_lo);
pci_read_config_byte(dev, PCI_IO_LIMIT, &io_limit_lo);
base = (io_base_lo & io_mask) << 8;
@@ -384,15 +381,12 @@ static void pci_read_bridge_io(struct pci_bus *child)
}
}

-static void pci_read_bridge_mmio(struct pci_bus *child)
+static void pci_read_bridge_mmio(struct pci_dev *dev, struct resource *res)
{
- struct pci_dev *dev = child->self;
u16 mem_base_lo, mem_limit_lo;
unsigned long base, limit;
struct pci_bus_region region;
- struct resource *res;

- res = child->resource[1];
pci_read_config_word(dev, PCI_MEMORY_BASE, &mem_base_lo);
pci_read_config_word(dev, PCI_MEMORY_LIMIT, &mem_limit_lo);
base = ((unsigned long) mem_base_lo & PCI_MEMORY_RANGE_MASK) << 16;
@@ -406,16 +400,13 @@ static void pci_read_bridge_mmio(struct pci_bus *child)
}
}

-static void pci_read_bridge_mmio_pref(struct pci_bus *child)
+static void pci_read_bridge_mmio_pref(struct pci_dev *dev, struct resource *res)
{
- struct pci_dev *dev = child->self;
u16 mem_base_lo, mem_limit_lo;
u64 base64, limit64;
pci_bus_addr_t base, limit;
struct pci_bus_region region;
- struct resource *res;

- res = child->resource[2];
pci_read_config_word(dev, PCI_PREF_MEMORY_BASE, &mem_base_lo);
pci_read_config_word(dev, PCI_PREF_MEMORY_LIMIT, &mem_limit_lo);
base64 = (mem_base_lo & PCI_PREF_RANGE_MASK) << 16;
@@ -527,9 +518,9 @@ void pci_read_bridge_bases(struct pci_bus *child)
for (i = 0; i < PCI_BRIDGE_RESOURCE_NUM; i++)
child->resource[i] = &dev->resource[PCI_BRIDGE_RESOURCES+i];

- pci_read_bridge_io(child);
- pci_read_bridge_mmio(child);
- pci_read_bridge_mmio_pref(child);
+ pci_read_bridge_io(child->self, child->resource[0]);
+ pci_read_bridge_mmio(child->self, child->resource[1]);
+ pci_read_bridge_mmio_pref(child->self, child->resource[2]);

if (dev->transparent) {
pci_bus_for_each_resource(child->parent, res) {
--
2.51.0