Re: [RFC/RFT PATCH] PCI: move pci_read_bridge_bases to the generic PCI layer

[Suravee Suthikulanit]

On 5/27/2015 12:54 PM, Lorenzo Pieralisi wrote:
> > > diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> > > > >index 062fee6..335d9f2 100644
> > > > >--- a/drivers/pci/probe.c
> > > > >+++ b/drivers/pci/probe.c
> > > > >@@ -453,7 +453,11 @@ void pci_read_bridge_bases(struct pci_bus *child)
> > > > >   	struct resource *res;
> > > > >   	int i;
> > > > >
> > > > >-	if (pci_is_root_bus(child))	/* It's a host bus, nothing to read */
> > > > >+	/*
> > > > >+	 * If it is not a PCI bridge there is nothing to read
> > > > >+	 */
> > > > >+	if (pci_is_root_bus(child) || !dev ||
> > > > >+		!((dev->class >> 8) == PCI_CLASS_BRIDGE_PCI))
> > > > >   		return;
> > > > >
> > > > >   	dev_info(&dev->dev, "PCI bridge to %pR%s\n",
> > > > >@@ -1878,6 +1882,11 @@ unsigned int pci_scan_child_bus(struct pci_bus *bus)
> > > > >   	 * all PCI-to-PCI bridges on this bus.
> > > > >   	 */
> > > > >   	if (!bus->is_added) {
> > > > >+		/*
> > > > >+		 * Read and initialize bridge resources.
> > > > >+		 */
> > > > >+		pci_read_bridge_bases(bus);
> > > > >+
> > > > >   		dev_dbg(&bus->dev, "fixups for bus\n");
> > > > >   		pcibios_fixup_bus(bus);
> > > > >   		bus->is_added = 1;
> > > > >
> > >
> > >So, I have tested the patch on ARM64 system w/ PROBE_ONLY mode, and
> > >noticed that we are calling pci_read_bridge_bases() after adding the
> > >devices on the slots. This is not soon enough since the downstream
> > >devices still failing to claim resources.
> > >
> > >However, do you think we can move pci_read_bridge_bases() before the
> > >pci_scan_slot() loop?
> Right, how about moving it to pci_scan_bridge() before calling the
> respective pci_scan_child_bus() ? I think it belongs there anyway.
>
> Thanks,

That seems reasonable. I test putting it here in pci_scan_bridge(),
and it works.

....
	child = pci_find_bus(pci_domain_nr(bus), secondary);
	if (!child) {
		child = pci_add_new_bus(bus, dev, secondary);
		if (!child)
			goto out;
		child->primary = primary;
		pci_bus_insert_busn_res(child, secondary, subordinate);
		child->bridge_ctl = bctl;
		pci_read_bridge_bases(child);
	}

	cmax = pci_scan_child_bus(child);
.....

Thanks,
Suravee
	


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