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

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Message-ID: <CA+sq2Ccp0_4hgbbWa27bkYcqiXY6Ckr8eckWnHwANvhWNo97fg@mail.gmail.com>
Date:	Wed, 21 May 2014 16:45:29 +0530
From:	Sunil Kovvuri <sunil.kovvuri@...il.com>
To:	Sunil Kovvuri <sunil.kovvuri@...il.com>,
	linux-pci <linux-pci@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Will Deacon <Will.Deacon@....com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	linaro-kernel <linaro-kernel@...ts.linaro.org>,
	Arnd Bergmann <arnd@...db.de>,
	LKML <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	LAKML <linux-arm-kernel@...ts.infradead.org>,
	Tanmay Inamdar <tinamdar@....com>,
	Grant Likely <grant.likely@...retlab.ca>,
	"kdb@...ndal.org" <kdb@...ndal.org>,
	"yu.zhao@...el.com" <yu.zhao@...el.com>
Subject: Re: [PATCH v7 0/3] Add support for PCI in AArch64

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.

Regards,
Sunil.


On Fri, May 16, 2014 at 11:12 PM, Sunil Kovvuri <sunil.kovvuri@...il.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@....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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