On Wed, May 06, 2015 at 10:32:48PM -0500, Suravee Suthikulanit wrote:
> ...
> I tested this patch series on the AMD Seattle w/o PCI_PROBE_ONLY
> mode and that works fine. However, w/ PCI_PROBE_ONLY, I also run
> into the resource not claimed issue (no surprise here).
>
> So, I tried porting the pcibios_claim_one_bus() from
> arch/alpha/kernel/pci.c as Lorenzo suggested, plus the a small
> change in pci_claim_resource(), and it seems to work w/
> PCI_PROBE_ONLY. (Please see example patch below.)
>
> The additional while loop is needed in the pci_claim_resource()
> since I need to reference back to the resource in the root bus,
> which are defined from the DT node. Does this sounds like a
> reasonable approach?
>
> diff --git a/drivers/pci/host/pci-host-generic.c
> b/drivers/pci/host/pci-host-generic.c
> index e9cc559..0dfa23d 100644
> --- a/drivers/pci/host/pci-host-generic.c
> +++ b/drivers/pci/host/pci-host-generic.c
> @@ -261,7 +261,10 @@ static int gen_pci_probe(struct platform_device *pdev)
> if (!pci_has_flag(PCI_PROBE_ONLY)) {
> pci_bus_size_bridges(bus);
> pci_bus_assign_resources(bus);
> + } else {
> + pci_claim_one_bus(bus);
> }
> +
> pci_bus_add_devices(bus);
>
> /* Configure PCI Express settings */
> diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c
> index 232f925..d4b43b3 100644
> --- a/drivers/pci/setup-res.c
> +++ b/drivers/pci/setup-res.c
> @@ -109,6 +109,7 @@ int pci_claim_resource(struct pci_dev *dev, int
> resource)
> {
> struct resource *res = &dev->resource[resource];
> struct resource *root, *conflict;
> + struct pci_dev *pdev = dev;
>
> if (res->flags & IORESOURCE_UNSET) {
> dev_info(&dev->dev, "can't claim BAR %d %pR: no address assigned\n",
> @@ -116,7 +117,18 @@ int pci_claim_resource(struct pci_dev *dev, int
> resource)
> return -EINVAL;
> }
>
> - root = pci_find_parent_resource(dev, res);
> + while (pdev) {
> + root = pci_find_parent_resource(pdev, res);
> + if (root)
> + break;
> +
> + if (pci_has_flag(PCI_PROBE_ONLY) &&
> + !pci_is_root_bus(pdev->bus))
> + pdev = pdev->bus->self;
> + else
> + break;
> + }
I don't understand this new loop. Apparently you have a device BAR, and
the upstream bridge doesn't have a window that contains the BAR? That
sounds like a problem with the upstream bridge resources.
Do you have an example that would make this more concrete, e.g., a host
bridge, P2P bridge(s), and endpoint with their resources?
> +
> if (!root) {
> dev_info(&dev->dev, "can't claim BAR %d %pR: no compatible bridge
> window\n",
> resource, res);
> @@ -136,6 +148,36 @@ int pci_claim_resource(struct pci_dev *dev, int
> resource)
> }
> EXPORT_SYMBOL(pci_claim_resource);
>
> +void pci_claim_one_bus(struct pci_bus *b)
> +{
> + struct pci_dev *pdev;
> + struct pci_bus *child_bus;
> +
> + list_for_each_entry(pdev, &b->devices, bus_list) {
> + int i;
> +
> + for (i = 0; i < PCI_NUM_RESOURCES; i++) {
> + struct resource *r = &pdev->resource[i];
> +
> + if (r->parent || !r->start || !r->flags)
> + continue;
> +
> + if (pci_has_flag(PCI_PROBE_ONLY) ||
> + (r->flags & IORESOURCE_PCI_FIXED)) {
> + if (pci_claim_resource(pdev, i) == 0)
> + continue;
> +
> + pci_claim_bridge_resource(pdev, i);
> + }
> + }
> + }
> +
> + list_for_each_entry(child_bus, &b->children, node) {
> + pci_claim_one_bus(child_bus);
> + }
> +}
> +EXPORT_SYMBOL(pci_claim_one_bus);
I'm not a fan of pci_claim_one_bus(), on the philosophical grounds that
claiming resources is a per-device thing, and I don't want to encourage
people to do it on a per-bus level.
I'd rather claim them somewhere in the pci_device_add() path, as s390 does
in pcibios_add_device(). In fact, I'd *like* to do it even earlier, when
we read each BAR, so we could identify invalid or unassigned BARs
immediately.
> +
> void pci_disable_bridge_window(struct pci_dev *dev)
> {
> dev_info(&dev->dev, "disabling bridge mem windows\n");
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 353db8d..b59ad4b 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1085,6 +1085,7 @@ void
> pci_assign_unassigned_bridge_resources(struct pci_dev *bridge);
> void pci_assign_unassigned_bus_resources(struct pci_bus *bus);
> void pci_assign_unassigned_root_bus_resources(struct pci_bus *bus);
> void pdev_enable_device(struct pci_dev *);
> +void pci_claim_one_bus(struct pci_bus *b);
> int pci_enable_resources(struct pci_dev *, int mask);
> void pci_fixup_irqs(u8 (*)(struct pci_dev *, u8 *),
> int (*)(const struct pci_dev *, u8, u8));
> -------- END PATCH ----
>
> Thanks,
>
> Suravee
>
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