Re: [Query] : PCIe - Endpoint Function

[Kishon Vijay Abraham I <kishon@ti.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