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

Sunil Kovvuri
2014-05-20T04:22:33Z

On Mon, May 19, 2014 at 6:31 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Friday 16 May 2014 16:03:04 Sunil Kovvuri wrote:
>> 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".
>
> I assume you have checked that there is indeed enough MMIO space
> available, right?
>
Yes, i have checked for enough MMIO space multiple times.

>> 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'.
>
> This looks like the wrong approach. The PCI host controller should
> really have been registered with the root 'iomem_resource' during
> the probe of the host controller.
>
> Arnd
I didn't get this, if a SR-IOV device is connected to a PCI-PCI bridge
and inturn bridge connected to root port. Then the parent bus is not root,
but the bridge. The issue is either hierarchy should not be checked for
SR-IOV resources or someone should set the hierarchy (i.e parent resources).

Regards,
Sunil.