Re: [PATCH 18/28] PCI/sparc: Use pci_scan_root_bridge() for simplicity

Arnd Bergmann
2015-01-19T08:45:41Z

On Monday 19 January 2015 11:17:02 Yijing Wang wrote:
> On 2015/1/16 18:01, Arnd Bergmann wrote:
> > On Friday 16 January 2015 09:44:16 Yijing Wang wrote:
> >> +static void pci_host_bridge_probe_mode(
> >> + struct pci_host_bridge *host)
> >> +{
> >> + host->of_scan = true;
> >> +}
> >>
> >
> > I probably missed something here, but where does host->of_scan
> > get used?
> >
>
> It is used in __pci_scan_root_bus() to detect whether of scan bus is needed in patch 11.

Ok, I see it now.

> @@ -2051,10 +2053,17 @@ static struct pci_bus *__pci_scan_root_bus(
> pci_bus_insert_busn_res(b, host->busnum, 255);
> }
>
> - max = pci_scan_child_bus(b);
> + if (host->ops && host->ops->phb_probe_mode)
> + host->ops->phb_probe_mode(host);
>
> - if (!found)
> - pci_bus_update_busn_res_end(b, max);
> + if (host->of_scan) {
> + if (host->ops &&host->ops->phb_of_scan_bus)
> + host->ops->phb_of_scan_bus(host);
> + } else {
> + max = pci_scan_child_bus(b);
> + if (!found)
> + pci_bus_update_busn_res_end(b, max);
> + }
>

I think we can simplify this based on the knowledge that this code
will remain powerpc specific. How about removing the phb_probe_mode()
callback and replacing it with just a phb_scan_bus() callback that
will always get set on sparc, and do this on powerpc:

+static void pci_host_bridge_of_scan_bus(struct pci_host_bridge *host)
+{
+ int mode = PCI_PROBE_NORMAL;
+ struct pci_bus *bus = host->bus;
+ struct pci_controller *hose = dev_get_drvdata(&host->dev);
+
+ /* Get probe mode and perform scan */
+ if (hose->dn && ppc_md.pci_probe_mode)
+ mode = ppc_md.pci_probe_mode(bus);
+
+ pr_debug(" probe mode: %d\n", mode);
+ if (mode == PCI_PROBE_DEVTREE) {
+ of_scan_bus(host->dn, bus);
+ return max; // XXX need to get this from somewhere
+ }
+ return pci_scan_child_bus(b);
+}

Would that work?

Arnd