[v2] PCI: host-common: Request bus reassignment when not probe-only

[PATCH v2] PCI: host-common: Request bus reassignment when not probe-only

Posted by Ratheesh Kannoth 2 months ago

pci_host_common_init() is used by several generic ECAM host drivers.
After PCI core changes around pci_flags and preserve_config, these hosts
no longer opted into full bus number reassignment the way they did
before.

When PCI_PROBE_ONLY is not set, add PCI_REASSIGN_ALL_BUS so
pci_scan_bridge_extend() takes the reassignment path: bus numbers can be
assigned from firmware EA data (e.g. pci_ea_fixed_busnrs()). Skip the
flag in probe-only mode so existing assignments are not overridden.

CC: Bjorn Helgaas <helgaas@kernel.org>
CC: Vidya Sagar <vidyas@nvidia.com>
CC: Manivannan Sadhasivam <mani@kernel.org>
Fixes: 7246a4520b4b ("PCI: Use preserve_config in place of pci_flags")
Link: https://lore.kernel.org/netdev/adcXzcz2wWJFw4d7@rkannoth-OptiPlex-7090/
Signed-off-by: Ratheesh Kannoth <rkannoth@marvell.com>

---
v1 -> v2 : https://lore.kernel.org/linux-pci/20260410142124.2673056-1-rkannoth@marvell.com/
---
 drivers/pci/controller/pci-host-common.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/pci/controller/pci-host-common.c b/drivers/pci/controller/pci-host-common.c
index d6258c1cffe5..99952fb7189b 100644
--- a/drivers/pci/controller/pci-host-common.c
+++ b/drivers/pci/controller/pci-host-common.c
@@ -68,6 +68,10 @@ int pci_host_common_init(struct platform_device *pdev,
 	if (IS_ERR(cfg))
 		return PTR_ERR(cfg);
 
+	/* Do not reassign bus numbers if probe only */
+	if (!pci_has_flag(PCI_PROBE_ONLY))
+		pci_add_flags(PCI_REASSIGN_ALL_BUS);
+
 	bridge->sysdata = cfg;
 	bridge->ops = (struct pci_ops *)&ops->pci_ops;
 	bridge->enable_device = ops->enable_device;
-- 
2.43.0

Re: [PATCH v2] PCI: host-common: Request bus reassignment when not probe-only

Posted by Bjorn Helgaas 1 month, 1 week ago

On Tue, Apr 14, 2026 at 01:47:30PM +0530, Ratheesh Kannoth wrote:
> pci_host_common_init() is used by several generic ECAM host drivers.
> After PCI core changes around pci_flags and preserve_config, these hosts
> no longer opted into full bus number reassignment the way they did
> before.
> 
> When PCI_PROBE_ONLY is not set, add PCI_REASSIGN_ALL_BUS so
> pci_scan_bridge_extend() takes the reassignment path: bus numbers can be
> assigned from firmware EA data (e.g. pci_ea_fixed_busnrs()). Skip the
> flag in probe-only mode so existing assignments are not overridden.
> 
> CC: Bjorn Helgaas <helgaas@kernel.org>
> CC: Vidya Sagar <vidyas@nvidia.com>
> CC: Manivannan Sadhasivam <mani@kernel.org>
> Fixes: 7246a4520b4b ("PCI: Use preserve_config in place of pci_flags")
> Link: https://lore.kernel.org/netdev/adcXzcz2wWJFw4d7@rkannoth-OptiPlex-7090/
> Signed-off-by: Ratheesh Kannoth <rkannoth@marvell.com>

Thanks for the fix!  Was there a bug report associated with this?  Is
there a symptom we can mention so we can connect the problem to this
solution?

Re: [PATCH v2] PCI: host-common: Request bus reassignment when not probe-only

Posted by Manivannan Sadhasivam 1 month, 2 weeks ago

On Tue, 14 Apr 2026 13:47:30 +0530, Ratheesh Kannoth wrote:
> pci_host_common_init() is used by several generic ECAM host drivers.
> After PCI core changes around pci_flags and preserve_config, these hosts
> no longer opted into full bus number reassignment the way they did
> before.
> 
> When PCI_PROBE_ONLY is not set, add PCI_REASSIGN_ALL_BUS so
> pci_scan_bridge_extend() takes the reassignment path: bus numbers can be
> assigned from firmware EA data (e.g. pci_ea_fixed_busnrs()). Skip the
> flag in probe-only mode so existing assignments are not overridden.
> 
> [...]

Applied, thanks!

[1/1] PCI: host-common: Request bus reassignment when not probe-only
      commit: 76d06fb36e8e6d1705fbbf75a450e5725199ed5f

Best regards,
-- 
Manivannan Sadhasivam <mani@kernel.org>