DMA-buf and uncached system memory

Christian König christian.koenig at amd.com
Thu Jun 23 08:26:45 UTC 2022


Am 23.06.22 um 10:13 schrieb Thomas Zimmermann:
> Hi Christian
>
> Am 15.02.21 um 09:58 schrieb Christian König:
>> Hi guys,
>>
>> we are currently working an Freesync and direct scan out from system 
>> memory on AMD APUs in A+A laptops.
>>
>> On problem we stumbled over is that our display hardware needs to 
>> scan out from uncached system memory and we currently don't have a 
>> way to communicate that through DMA-buf.
>>
>> For our specific use case at hand we are going to implement something 
>> driver specific, but the question is should we have something more 
>> generic for this?
>
> I had a patchset here that extends iosys-map (former dma-buf-map) with 
> caching information. I'll post a copy.

Oh, nice. But why on iosys-map? We need that per DMA-buf.

Thanks,
Christian.

>
> Sorry for being late to reply.
>
> Best regards
> Thomas
>
>>
>> After all the system memory access pattern is a PCIe extension and as 
>> such something generic.
>>
>> Regards,
>> Christian.
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>



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