DMA-buf and uncached system memory

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?

After all the system memory access pattern is a PCIe extension and as such something generic.

Regards, Christian.