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From: Kishon Vijay Abraham I <kishon@ti.com>
To: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Cc: <linux-pci@vger.kernel.org>
Subject: Re: [Query] : PCIe - Endpoint Function
Date: Tue, 15 Oct 2019 13:22:44 +0530
Message-ID: <1ccb98e7-837d-059a-1292-f001b4bb66c6@ti.com> (raw)
In-Reply-To: <CA+V-a8vR+xar-TsTOiBtNfbYuP8Wb_ktuf-i7tOkQ+==rs7Rug@mail.gmail.com>

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?

Thanks
Kishon

  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-10 11:27 Lad, Prabhakar
2019-10-10 11:32 ` Kishon Vijay Abraham I
2019-10-11  7:35   ` Lad, Prabhakar
2019-10-11 13:37     ` Lad, Prabhakar
2019-10-15  7:52       ` Kishon Vijay Abraham I [this message]
2019-10-22  6:06         ` Lad, Prabhakar
2019-10-29 10:24           ` Lad, Prabhakar
2019-10-29 10:53             ` Kishon Vijay Abraham I
2019-10-29 14:55               ` Lad, Prabhakar

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