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SubjectRe: [PATCH v3 05/11] PCI: beef up pci_do_scan_bus()
Alex Chiang wrote:
> Hello Kenji-san,
>
> * Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>:
>> Alex Chiang wrote:
>>> We have a nice interface for re-scanning a PCI bus which will
>>> discover newly added devices, add them to the device tree, and
>>> enable them properly.
>>>
>>> Ensure that the bridge resources are properly sized and assigned
>>> during the rescan.
>>>
>>> Signed-off-by: Alex Chiang <achiang@hp.com>
>>> ---
>>>
>>> drivers/pci/hotplug-pci.c | 16 ++++++++++++----
>>> 1 files changed, 12 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/pci/hotplug-pci.c b/drivers/pci/hotplug-pci.c
>>> index 4d4a644..33ab2d2 100644
>>> --- a/drivers/pci/hotplug-pci.c
>>> +++ b/drivers/pci/hotplug-pci.c
>>> @@ -6,13 +6,21 @@
>>>
>>> unsigned int __devinit pci_do_scan_bus(struct pci_bus *bus)
>>> {
>>> - unsigned int max;
>>> + unsigned int max, pass;
>>> + struct pci_dev *dev;
>>>
>>> max = pci_scan_child_bus(bus);
>>>
>>> - /*
>>> - * Make the discovered devices available.
>>> - */
>>> + for (pass=0; pass < 2; pass++)
>>> + list_for_each_entry(dev, &bus->devices, bus_list) {
>>> + if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE ||
>>> + dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)
>>> + if (pass && dev->subordinate)
>>> + pci_bus_size_bridges(dev->subordinate);
>>> + }
>>> +
>>> + pci_bus_assign_resources(bus);
>>> + pci_enable_bridges(bus);
>>> pci_bus_add_devices(bus);
>> The "for (pass=0; pass <2; pass++)" loop doesn't look necessary.
>
> Yes, I don't know why I had it in there originally. I can remove
> that.
>
>> And I'm worrying that your change have some bad effect to the
>> existing user of pci_do_scan_bus(). Did you confirm that?
>
> I hadn't gotten around to verifying/fixing existing callers of
> pci_do_scan_bus yet. I was focusing on the core first.
>
> There aren't too many callers, but unfortunately, I don't have
> any hardware that actually uses the existing drivers.
>
> I seem to recall that your machines support shpchp. Would you
> mind testing this patch and telling me if your machine still
> behaves properly?
>

I have machines that support shpchp. But unfortunately I don't
have any adapter card that contains bridge, which is needed to
test your change.

> I looked at shpchp_configure_device and I think that simply
> scanning the device's parent bus should work.
>

Ok, I'll try it.

Thanks,
Kenji Kaneshige


> Thanks.
>
> /ac
>
> diff --git a/drivers/pci/hotplug/shpchp_pci.c b/drivers/pci/hotplug/shpchp_pci.c
> index aa315e5..7e8457b 100644
> --- a/drivers/pci/hotplug/shpchp_pci.c
> +++ b/drivers/pci/hotplug/shpchp_pci.c
> @@ -110,11 +110,7 @@ int __ref shpchp_configure_device(struct slot *p_slot)
> return -EINVAL;
> }
>
> - num = pci_scan_slot(parent, PCI_DEVFN(p_slot->device, 0));
> - if (num == 0) {
> - ctrl_err(ctrl, "No new device found\n");
> - return -ENODEV;
> - }
> + pci_do_scan_bus(parent);
>
> for (fn = 0; fn < 8; fn++) {
> dev = pci_get_slot(parent, PCI_DEVFN(p_slot->device, fn));
> @@ -126,40 +122,10 @@ int __ref shpchp_configure_device(struct slot *p_slot)
> pci_dev_put(dev);
> continue;
> }
> - if ((dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) ||
> - (dev->hdr_type == PCI_HEADER_TYPE_CARDBUS)) {
> - /* Find an unused bus number for the new bridge */
> - struct pci_bus *child;
> - unsigned char busnr, start = parent->secondary;
> - unsigned char end = parent->subordinate;
> - for (busnr = start; busnr <= end; busnr++) {
> - if (!pci_find_bus(pci_domain_nr(parent),
> - busnr))
> - break;
> - }
> - if (busnr > end) {
> - ctrl_err(ctrl,
> - "No free bus for hot-added bridge\n");
> - pci_dev_put(dev);
> - continue;
> - }
> - child = pci_add_new_bus(parent, dev, busnr);
> - if (!child) {
> - ctrl_err(ctrl, "Cannot add new bus for %s\n",
> - pci_name(dev));
> - pci_dev_put(dev);
> - continue;
> - }
> - child->subordinate = pci_do_scan_bus(child);
> - pci_bus_size_bridges(child);
> - }
> program_fw_provided_values(dev);
> pci_dev_put(dev);
> }
>
> - pci_bus_assign_resources(parent);
> - pci_bus_add_devices(parent);
> - pci_enable_bridges(parent);
> return 0;
> }
>
>



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