Re: [PATCH v8 16/23] dma-buf: Let importers ask how peer-to-peer traffic is routed

["Christian König" <christian.koenig@amd.com>]

On 9/29/26 15:23, Leon Romanovsky wrote:
> On Tue, Sep 29, 2026 at 11:34:05AM +0200, Christian König wrote:
>> On 9/28/26 13:19, Leon Romanovsky wrote:
...>>
>>> +	return pci_p2pdma_map_type_tlp(provider, attach->dev, tlp_flags);
>>
>> This function call here *must* be in the exporter and not the DMA-buf framework.
>>
>> So clear NAK to putting that here.
> 
> "Look, it is easy to complain you don't like how it looks, but this
> stuff is hard there are lots of competing concerns, if you have a
> better idea now is a good time to present it."
> https://lore.kernel.org/all/20260921130858.GO11599@ziepe.ca/#t
> 
> Do you have a viable solution?

Ok, that sounds like you haven't understood why I'm rejecting this.

By moving the calls to pci_p2pdma functions into DMA-buf you bypass the NAK to expose those functions to drivers from the DMA maintainers.

I unfortunately didn't understood that when the dma-buf-mapping.c code was added and just assumed that you just needed a place to put some common code.

So as long as that NAK from the DMA maintainers to expose the pci_p2p functions to drivers stand I will push hard to get that stuff removed again from DMA-buf as well.

What you try to do here is seriously not ok and I will push back hard on that in the future.

Regards,
Christian.

> 
> Thanks
> 
>>
>> Regards,
>> Christian.