Re: [Query] : PCIe - Endpoint Function

["Lad, Prabhakar" <prabhakar.csengg@gmail.com>]

Hi Kishon,

On Tue, Oct 22, 2019 at 7:06 AM Lad, Prabhakar
<prabhakar.csengg@gmail.com> wrote:
>
> Hi Kishon,
>
>
> On Tue, Oct 15, 2019 at 8:53 AM Kishon Vijay Abraham I <kishon@ti.com> wrote:
> >
> > Hi Prabhakar,
> >
> > On 11/10/19 7:07 PM, Lad, Prabhakar wrote:
> > > Hi Kishon
> > >
> > > On Fri, Oct 11, 2019 at 8:35 AM Lad, Prabhakar
> > > <prabhakar.csengg@gmail.com> wrote:
> > >>
> > >> Hi Kishon,
> > >>
> > >> On Thu, Oct 10, 2019 at 12:32 PM Kishon Vijay Abraham I <kishon@ti.com> wrote:
> > >>>
> > >>> Hi Prabhakar,
> > >>>
> > >>> On 10/10/19 4:57 PM, Lad, Prabhakar wrote:
> > >>>> Hello,
> > >>>>
> > >>>> I am currently working on adding pcie-endpoint support for a
> > >>>> controller, this controller doesn't support outbound- inbound address
> > >>>> translations, it has 1-1 mapping between the CPU and PCI addresses,
> > >>>> the current endpoint framework is based on  outbound-inbound
> > >>>> translations, what is the best approach to add this support, or is
> > >>>> there any WIP already for it ?
> > >>>
> > >>> How will the endpoint access host buffer without outbound ATU? I assume the PCI
> > >>> address reserved for endpoint is not the full 32-bit or 64-bit address space?
> > >>> In that case, the endpoint cannot directly access the host buffer (unless the
> > >>> host already knows the address space of the endpoint and gives the endpoint an
> > >>> address in its OB address space).
> > >>>
> > > I lied in my previous mail.
> > >
> > > a] The controller needs the cpu_address before starting the link, ie
> > > with the current implementation,the bars physical address in endpoint
> > > are assigned
> > > using dma_alloc_coherent(), but I what I actually want here is the
> > > phys_addr returned by pci_epc_mem_alloc_addr().
> > >
> > > b] In the pci_endpoint_test driver, the pci_address sent to the
> > > endpoint driver is again dma_alloc_coherent(), but the address which I
> > > actually want to
> > > send to endpoint is the BAR's assigned regions in the RC.
> >
> > The BAR assigned regions are usually used by RC to access EP memory.
> > dma_alloc_coherent() is used in pci_endpoint_test to allocate buffer in host
> > memory to be accessed by EP. Can you again check if statement 'b' is accurate?
> >
> yes you were correct, I misread the manual I have a rough driver
> working now, will post as
> soon as I tidy it up.
>
after several runs of pcitest I hit the following issue any pointers
on would this be the RC/endpoint ?

[  153.637906] Internal error: synchronous external abort: 96000210
[#1] PREEMPT SMP
[  153.664156] Workqueue: kpcitest pci_epf_test_cmd_handler
[  153.669505] pstate: 80000005 (Nzcv daif -PAN -UAO)
[  153.674333] pc : __memcpy_fromio+0x40/0x80
[  153.678456] lr : pci_epf_test_cmd_handler+0x44c/0x670
[  153.683537] sp : ffff8000123abd10
[  153.686871] x29: ffff8000123abd10 x28: 0000000000000000
[  153.692217] x27: ffff000076b20000 x26: ffff8000124a0000
[  153.697563] x25: ffff000076ecd000 x24: ffff00007c4ac000
[  153.702909] x23: ffff800011bb9000 x22: ffff00007af7cc80
[  153.708254] x21: ffff800011bb9000 x20: ffff800010eef000
[  153.713600] x19: ffff00007af7ccc0 x18: 0000000000000000
[  153.718946] x17: 0000000000000000 x16: 0000000000000000
[  153.724291] x15: 0000000000000000 x14: 0000000000000000
[  153.729637] x13: 0000000000000000 x12: 0000000000000001
[  153.734984] x11: 0000000000000002 x10: 0000000000000050
[  153.740330] x9 : ffff00007dbf2d98 x8 : 0000000000000000
[  153.745676] x7 : 0000000000000001 x6 : 0000000000019000
[  153.751021] x5 : ffff000076b39000 x4 : e7c67145d9acb067
[  153.756367] x3 : ffff8000124afa78 x2 : 0000000000019000
[  153.761714] x1 : ffff8000124a0000 x0 : ffff000076b2fa78
[  153.767063] Call trace:
[  153.769527]  __memcpy_fromio+0x40/0x80
[  153.773307]  process_one_work+0x29c/0x718
[  153.777343]  worker_thread+0x40/0x460
[  153.781032]  kthread+0x11c/0x120
[  153.784285]  ret_from_fork+0x10/0x18
[  153.787887] Code: aa0103e3 927df0c6 910020c6 8b060005 (f9400064)
[  153.794024] ---[ end trace d88a2a6a414998d3 ]---

Cheers,
--Prabhakar