Re: Linux PCIe EP NTB function

[Kishon Vijay Abraham I <kishon@ti.com>]

Hi Frank,

On 15/10/21 2:10 am, Frank Li wrote:
> Sorry, correct Linux-pci mail list address.
> 
>> -----Original Message-----
>> From: Frank Li
>> Sent: Thursday, October 14, 2021 3:35 PM
>> To: kishon@ti.com; kw@linux.com; Sherry Sun <sherry.sun@nxp.com>; Richard
>> Zhu <hongxing.zhu@nxp.com>
>> Cc: inux-pci@vger.kernel.org
>> Subject: Linux PCIe EP NTB function
>>
>> Kishon:
>>
>> 	We use VOP(virtio over PCIe) communication between PCI RC and EP side.
>> But VOP already removed and switch into NTB solution.
>> 	I saw you submit patch and already accepted by community about pci-
>> epf-ntb.
>>
>> 	According to document, whole system work as Device1 (PCI host) -> EP1
>> -> EP2 -> Device2(PCI host).
>> 	But our user case is Device 1(RC Host) ->  Device 2(EP).
>>
>> 	I am not sure how to apply ntb frame work into this user case.

NTB by definition is PCIe RC-to-RC communication. For RC-to-EP, see
pci_endpoint_test.c (RC) and pci-epf-test.c (EP) that provides sample endpoint
usecase.

One more RC<->EP communication model was built in [1], but that is not yet
upstreamed.

[1] -> https://lore.kernel.org/r/20200702082143.25259-1-kishon@ti.com

Thanks,
Kishon

>>
>> 	I think we can modify pci-epf-ntb to register a ntb devices. But I am
>> not sure that this is recommunicate method.  I think this user case is
>> quite common. I don't want to implement a local solution.
>>
>> 	Any suggestion?
>>
>>
>> Best regards
>> Frank Li