AXI MCDMA support?
Livius90 opened this issue · comments
Hi,
Is the AXI Multichannel DMA supported to use with u-dma-buf?
The maximum number of DMA buffers that can be allocated using insmod is 8 (udmabuf0/1/2/3/4/5/6/7).
What does it mean? Maximum 8 DMA buffer is limited only, if it is configured via insmod? What is the maximum if they are defined in device-tree nodes instead of insmod?
Thank you for the issue.
I am not familiar with AXI MCDMA.
u-dma-buf only provides DMA buffers, it does not control DMA.
There is probably a dedicated Linux Driver for AXI MCDMA.
Please contact AMD for more information.
I'm sorry I couldn't help you.
Hi,
I looked after what is the different between AXI DMA and AXI MCDMA, lets see the following:
- AXI DMA supported modes:
- Optional Independent Scatter/Gather Direct Memory Access (DMA) support
- Optional Direct Register Mode (no scatter/gather support)
- AXI MCDMA supported modes:
- Scatter/Gather support (only)
As i understand your u-dma-buf kernel module, it supports only the "Direct Register Mode" and "Scatter/Gather" is not supported, am i rigth? In this case AXI MCDMA is not usable via u-dma-buf unfortunately. 😢
The maximum number of DMA buffers that can be allocated using insmod is 8 (udmabuf0/1/2/3/4/5/6/7).
What does it mean? Maximum 8 DMA buffer is limited only, if it is configured via insmod? What is the maximum if they are defined in device-tree nodes instead of insmod?
What does it mean? Maximum 8 DMA buffer is limited only, if it is configured via insmod? What is the maximum if they are defined in device-tree nodes instead of insmod?
256
See u-dma-buf.c for details.
What does it mean? Maximum 8 DMA buffer is limited only, if it is configured via insmod? What is the maximum if they are defined in device-tree nodes instead of insmod?
256
See u-dma-buf.c for details.
Thanks, i found it in the code:
https://github.com/ikwzm/udmabuf/blob/master/u-dma-buf.c#L72
Thanks the detailed quick answers, your u-dma-buf is awesome.