Does Xavier support coherent DMA?

Xilinx’s DMA Engine IP has a companion sample X86 linux driver implementation.

Xilinx asserts this sample code is not supported on ARM.

Eli the Xillybus Guy asserts (to paraphrase): X86 has coherent DMA and ARM platforms generally do not.

Coherent DMA is defined as an intrinsic mechanism that allows the CPU to know that memory address segments that in it’s cache working set have been invalidated because DMA has just changed the data in the currently cached memory segments.

What is the status of this behavior on Xavier? Please let me know.

If further questions need to be asked of me to better understand what i am talking about, dont hesitate to ask them!

Tnx!

johnu

Hi,
We do not support it on Xavier.
We have our own DMA buffer implementation named NvBuffer in tegra_multimedia_api. Please check
https://docs.nvidia.com/jetson/archives/l4t-multimedia-archived/l4t-multimedia-311/index.html
https://developer.nvidia.com/embedded/dlc/l4t-multimedia-api-reference-31-1-0

You can install the samples via Jetpack.

Thankyou, I will read the docs and either accept the answer or follow up with further questions by EOD.

Tnx!

johnu

Hello DaneLLL;

How do I mark this as answered?

Tnx!

johnu

Hello,

I converted this topic to an “issue”, you can now mark as “answered”.

Best,
Tom