Re: [PATCH v7 0/3] Add support for PCI in AArch64

Sunil Kovvuri
2014-05-16T10:33:04Z

Hi Liviu,

I am using your ARM64 PCIe patches to write a PCIe host controller
driver for our SOC. I am facing an issue with SR-IOV capable device.

Consider an PCI Express endpoint connected to a PCI Express
Root Port. The PCI Express endpoint provides PCI-SIG SR-IOV
capabilities with a single physical function and a large number
of virtual functions. The Root Port contains a pci-pci bridge in
between it and the SR-IOV device.

When the SR-IOV capable device's driver tries to enable sriov
(pci_enable_sriov()) it fails to create/add PCI device for each
virtual function reporting "not enough MMIO resources for SR-IOV".

In sriov_enable() (drivers/pci/iov.c)

296 for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
297 bars |= (1 << (i + PCI_IOV_RESOURCES));
298 res = dev->resource + PCI_IOV_RESOURCES + i;
299 if (res->parent)
300 nres++;
301 }
302 if (nres != iov->nres) {
303 dev_err(&dev->dev, "not enough MMIO resources for
SR-IOV\n");
304 return -ENOMEM;
305 }

Here its checking if physical function's IOV resource has a parent or not.
Which is pci-pci bridge in this case. Otherwise it doesn't consider
that resource.

Added below api to your patch.
This will try to claim a resource while creating a PCI device which
inturn sets 'res->parent'.

Let me know if this is okay.

diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
index 9f29c9a..fbfb48f 100644
--- a/arch/arm64/kernel/pci.c
+++ b/arch/arm64/kernel/pci.c
@@ -125,6 +125,21 @@ resource_size_t pcibios_align_resource(void
*data, const struct resource *res,
return res->start;
}

+int pcibios_add_device(struct pci_dev *pdev)
+{
+ unsigned int i, type_mask = IORESOURCE_IO | IORESOURCE_MEM;
+ struct resource *res;
+
+ for (i = 0; i < PCI_NUM_RESOURCES; i++) {
+ res = &pdev->resource[i];
+ if (res->parent || !(res->flags & type_mask))
+ continue;
+ pci_claim_resource(pdev, i);
+ }
+

On Fri, Mar 14, 2014 at 9:04 PM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> Hi,
>
> This patch adds support for PCI to AArch64. It is based on my v7 patch
> that adds support for creating generic host bridge structure from
> device tree. With that in place, I was able to boot a platform that
> has PCIe host bridge support and use a PCIe network card.
>
> I have dropped the RFC tag from the subject as I now have the ambitious goal
> of trying to get it mainlined.
>
> Changes from v6:
> - Guard the pci_domain_nr() inline implementation with #ifdef CONFIG_PCI as
> to avoid conflict with default empty version present in include/linux/pci.h.
> Thanks to Jingoo Han for catching this.
>
> Changes from v5:
> - Removed pcibios_fixup_bridge_ranges() as the week default version is fine.
> - Removed the ALIGN() call in pcibios_align_resource()
> - Stopped exporting pcibios_align_resource()
>
> Changes from v4:
> - Fixed the pci_domain_nr() implementation for arm64. Now we use
> find_pci_host_bride() to find the host bridge before we retrieve
> the domain number.
>
> Changes from v3:
> - Added Acks accumulated so far ;)
> - Still carrying Catalin's patch for moving the PCI_IO_BASE until it
> lands in linux-next or mainline, in order to ease applying the series
>
> Changes from v2:
> - Implement an arch specific version of pci_register_io_range() and
> pci_address_to_pio().
> - Return 1 from pci_proc_domain().
>
> Changes from v1:
> - Added Catalin's patch for moving the PCI_IO_BASE location and extend
> its size to 16MB
> - Integrated Arnd's version of pci_ioremap_io that uses a bitmap for
> keeping track of assigned IO space and returns an io_offset. At the
> moment the code is added in arch/arm64 but it can be moved in drivers/pci.
> - Added a fix for the generic ioport_map() function when !CONFIG_GENERIC_IOMAP
> as suggested by Arnd.
>
> v6 thread here: https://lkml.org/lkml/2014/3/5/41
> v5 thread here: https://lkml.org/lkml/2014/3/4/307
> v4 thread here: https://lkml.org/lkml/2014/3/3/298
> v3 thread here: https://lkml.org/lkml/2014/2/28/211
> v2 thread here: https://lkml.org/lkml/2014/2/27/255
> v1 thread here: https://lkml.org/lkml/2014/2/3/389
>
>
> The API used is different from the one used by ARM architecture. There is
> no pci_common_init_dev() function and no hw_pci structure, as that is no
> longer needed. Once the last signature is added to the legal agreement, I
> will post the host bridge driver code that I am using. Meanwhile, here
> is an example of what the probe function looks like, posted as an example:
>
> static int myhostbridge_probe(struct platform_device *pdev)
> {
> int err;
> struct device_node *dev;
> struct pci_host_bridge *bridge;
> struct myhostbridge_port *pp;
> resource_size_t lastbus;
>
> dev = pdev->dev.of_node;
>
> if (!of_device_is_available(dev)) {
> pr_warn("%s: disabled\n", dev->full_name);
> return -ENODEV;
> }
>
> pp = kzalloc(sizeof(struct myhostbridge_port), GFP_KERNEL);
> if (!pp)
> return -ENOMEM;
>
> bridge = of_create_pci_host_bridge(&pdev->dev, &myhostbridge_ops, pp);
> if (IS_ERR(bridge)) {
> err = PTR_ERR(bridge);
> goto bridge_create_fail;
> }
>
> err = myhostbridge_setup(bridge->bus);
> if (err)
> goto bridge_setup_fail;
>
> /* We always enable PCI domains and we keep domain 0 backward
> * compatible in /proc for video cards
> */
> pci_add_flags(PCI_ENABLE_PROC_DOMAINS);
> pci_add_flags(PCI_REASSIGN_ALL_BUS | PCI_REASSIGN_ALL_RSRC);
>
> lastbus = pci_scan_child_bus(bridge->bus);
> pci_bus_update_busn_res_end(bridge->bus, lastbus);
>
> pci_assign_unassigned_bus_resources(bridge->bus);
>
> pci_bus_add_devices(bridge->bus);
>
> return 0;
>
> bridge_setup_fail:
> put_device(&bridge->dev);
> device_unregister(&bridge->dev);
> bridge_create_fail:
> kfree(pp);
> return err;
> }
>
> Best regards,
> Liviu
>
>
> Catalin Marinas (1):
> arm64: Extend the PCI I/O space to 16MB
>
> Liviu Dudau (2):
> Fix ioport_map() for !CONFIG_GENERIC_IOMAP cases.
> arm64: Add architecture support for PCI
>
> Documentation/arm64/memory.txt | 16 +--
> arch/arm64/Kconfig | 19 +++-
> arch/arm64/include/asm/Kbuild | 1 +
> arch/arm64/include/asm/io.h | 5 +-
> arch/arm64/include/asm/pci.h | 51 +++++++++
> arch/arm64/kernel/Makefile | 1 +
> arch/arm64/kernel/pci.c | 173 +++++++++++++++++++++++++++++++
> include/asm-generic/io.h | 2 +-
> 8 files changed, 258 insertions(+), 10 deletions(-)
> create mode 100644 arch/arm64/include/asm/pci.h
> create mode 100644 arch/arm64/kernel/pci.c
>
> --
> 1.9.0
>
> --
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