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    SubjectRe: [PATCH v9 19/30] powerpc/pci: Use pci_scan_host_bridge() for simplicity
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    I've been looking at this patch series for a while now, and I now
    believe it's ready on the PowerPC side.

    I was originally concerned that it would break odd corner cases,
    particularly where similar code appears (namely kernel/pci_hotplug.c and
    kernel/pci_of_scan.c). However, upon further examination, talking with
    Yijing, and some testing, I'm now convinced that it is indeed restricted
    to the generic code, and doesn't change behaviour.

    This is both a plus and a minus: because it's currently restricted to
    generic code, I'm confident it works, but the down side is that it
    doesn't yet simplify our arch-specific complexity. We'll need to do some
    more work on our side to reap the full benefits.

    I tested this entire series on a PowerNV machine, including doing EEH
    injection to trigger PCI hotplug:
    Tested-by: Daniel Axtens <dja@axtens.net>
    For completeness, it would be good to test it on Cell, as they are the
    only remaining user of pci_of_scan.c

    In conclusion, this patch is
    Reviewed-by: Daniel Axtens <dja@axtens.net>

    Regards,
    Daniel Axtens


    On Fri, 2015-04-03 at 17:25 +0800, Yijing Wang wrote:
    > Now we could use pci_scan_host_bridge() to scan
    > pci buses, provide powerpc specific pci_host_bridge_ops.
    >
    > Signed-off-by: Yijing Wang <wangyijing@huawei.com>
    > CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    > CC: linuxppc-dev@lists.ozlabs.org
    > ---
    > arch/powerpc/kernel/pci-common.c | 62 +++++++++++++++++++++++--------------
    > 1 files changed, 38 insertions(+), 24 deletions(-)
    >
    > diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
    > index 2c58200..50b32f6 100644
    > --- a/arch/powerpc/kernel/pci-common.c
    > +++ b/arch/powerpc/kernel/pci-common.c
    > @@ -773,6 +773,29 @@ void pcibios_set_root_bus_speed(struct pci_host_bridge *bridge)
    > return ppc_md.pcibios_set_root_bus_speed(bridge);
    > }
    >
    > +static int pci_host_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(hose->dn, bus);
    > +
    > + if (mode == PCI_PROBE_NORMAL) {
    > + pci_bus_update_busn_res_end(bus, 255);
    > + hose->last_busno = pci_scan_child_bus(bus);
    > + pci_bus_update_busn_res_end(bus, hose->last_busno);
    > + }
    > +
    > + return pci_bus_child_max_busnr(bus);
    > +}
    > +
    > /* This header fixup will do the resource fixup for all devices as they are
    > * probed, but not for bridge ranges
    > */
    > @@ -1585,6 +1608,11 @@ struct device_node *pcibios_get_phb_of_node(struct pci_bus *bus)
    > return of_node_get(hose->dn);
    > }
    >
    > +static struct pci_host_bridge_ops pci_host_ops = {
    > + .set_root_bus_speed = pcibios_set_root_bus_speed,
    > + .scan_bus = pci_host_scan_bus,
    > +};
    > +
    > /**
    > * pci_scan_phb - Given a pci_controller, setup and scan the PCI bus
    > * @hose: Pointer to the PCI host controller instance structure
    > @@ -1592,9 +1620,8 @@ struct device_node *pcibios_get_phb_of_node(struct pci_bus *bus)
    > void pcibios_scan_phb(struct pci_controller *hose)
    > {
    > LIST_HEAD(resources);
    > - struct pci_bus *bus;
    > + struct pci_host_bridge *host;
    > struct device_node *node = hose->dn;
    > - int mode;
    >
    > pr_debug("PCI: Scanning PHB %s\n", of_node_full_name(node));
    >
    > @@ -1609,30 +1636,17 @@ void pcibios_scan_phb(struct pci_controller *hose)
    > hose->busn.flags = IORESOURCE_BUS;
    > pci_add_resource(&resources, &hose->busn);
    >
    > + pci_host_ops.pci_ops = hose->ops;
    > /* Create an empty bus for the toplevel */
    > - bus = pci_create_root_bus(hose->parent, hose->global_number,
    > - hose->first_busno, hose->ops, hose, &resources);
    > - if (bus == NULL) {
    > - pr_err("Failed to create bus for PCI domain %04x\n",
    > - hose->global_number);
    > + host = pci_scan_host_bridge(hose->parent, hose->global_number,
    > + hose->first_busno, hose, &resources, &pci_host_ops);
    > + if (host == NULL) {
    > + pr_err("Failed to create host bridge for pci%04x:%02x\n",
    > + hose->global_number, hose->first_busno);
    > pci_free_resource_list(&resources);
    > return;
    > }
    > - hose->bus = bus;
    > -
    > - /* Get probe mode and perform scan */
    > - mode = PCI_PROBE_NORMAL;
    > - if (node && 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(node, bus);
    > -
    > - if (mode == PCI_PROBE_NORMAL) {
    > - pci_bus_update_busn_res_end(bus, 255);
    > - hose->last_busno = pci_scan_child_bus(bus);
    > - pci_bus_update_busn_res_end(bus, hose->last_busno);
    > - }
    > + hose->bus = host->bus;
    >
    > /* Platform gets a chance to do some global fixups before
    > * we proceed to resource allocation
    > @@ -1641,9 +1655,9 @@ void pcibios_scan_phb(struct pci_controller *hose)
    > ppc_md.pcibios_fixup_phb(hose);
    >
    > /* Configure PCI Express settings */
    > - if (bus && !pci_has_flag(PCI_PROBE_ONLY)) {
    > + if (host->bus && !pci_has_flag(PCI_PROBE_ONLY)) {
    > struct pci_bus *child;
    > - list_for_each_entry(child, &bus->children, node)
    > + list_for_each_entry(child, &host->bus->children, node)
    > pcie_bus_configure_settings(child);
    > }
    > }

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