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

Liviu Dudau
2014-05-21T11:34:49Z

On Wed, May 21, 2014 at 04:45:29PM +0530, Sunil Kovvuri wrote:
> Hi Liviu,
>
> Sorry for the trouble.
> I got why 'res->parent' is not set in my case.
> Basically my SR-IOV device has fixed resources, so resources will not
> be allocated/assigned and hence parent resource is not set.
> I will move the resource claiming to host controller driver as a fixup
> so that parent resource hierarchy is set.
>
> Thanks for the support.

Glad you worked out the cause for the problem. I will still at to my list of
ToDo things to investigate resource parenting with my patchset.

Best regards,
Liviu

>
> Regards,
> Sunil.
>
>
> On Fri, May 16, 2014 at 11:12 PM, Sunil Kovvuri <sunil.kovvuri@gmail.com> wrote:
> > Hi Liviu,
> >
> > Issue may not be only with SR-IOV resources.
> >
> > I am not an expert with Linux PCI core. But i am trying to understand
> > how even for a non SR-IOV capable device's resource, gets a parent
> > associated with it.
> >
> > When a PCI device driver calls pci_enable_device() which inturn calls
> > 'arch/arm64/kernel/pci.c' pcibios_enable_device() which uses Linux PCI core
> > API 'pci_enable_resources'. This API checks 'res->parent' for all
> > valid resources
> > before enabling them, otherwise it fails.
> > if (!r->parent) {
> > dev_err(&dev->dev, "device not available "
> > "(can't reserve %pR)\n", r);
> > return -EINVAL;
> > }
> >
> > Can you please let me know where this hierarchy is being set for
> > 'pcibios_enable_resources' to work.
> >
> > I could only find request_resource() API which sets the parent and
> > pci_claim_resource() uses this.
> >
> > Thanks,
> > Sunil.
> >
> > On Fri, May 16, 2014 at 6:54 PM, Liviu Dudau <Liviu.Dudau@arm.com> wrote:
> >> Hi Sunil,
> >>
> >> On Fri, May 16, 2014 at 11:33:04AM +0100, Sunil Kovvuri wrote:
> >>> 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);
> >>> + }
> >>> +
> >>>
> >>
> >> I would like not to have to add your patch in this file as I am trying to
> >> remove it entirely. I don't have an SR-IOV capable device in my setup so
> >> I am not able to debug your problem, but could you have a go and try to
> >> figure out why the SR-IOV resources do not get a parent associated with
> >> when they get created?
> >>
> >> Many thanks,
> >> Liviu
> >>
> >>
> >> --
> >> ====================
> >> | I would like to |
> >> | fix the world, |
> >> | but they're not |
> >> | giving me the |
> >> \ source code! /
> >> ---------------
> >> ¯\_(ツ)_/¯
> >>
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