Why has DMA_SG removed from the latest version of the LS104x LSDK and what is the alternative?

[Gyosun]

Hello,

I am using an LS104x custom board.

As the LSDK version was continuously updated, it was confirmed that the DMA scatter-gather(DMA_SG) mode was removed when the kernel was 4.9 or higher.

I was using DMA_SG mode because I need to optimize the time.

Why was it removed and what is the alternative?

I am trying to apply LSDK20.04.

Thank you!

Best Regards.

Gyosun.

[yipingwang]

I discussed this issue with LSDK development team.

DMA_SG mode has never been supported on LS1 and LS2 platforms in LSDK.

Because Linux source code with DMA S/G mode cannot be pushed to upstream.

[Gyosun]

Hi yipingwang,

So what method should you use?

Thank you!

Best Regards,

Gyosun.

[yipingwang]

We consider use S/G mode to improve large packets transmission performance, splitting the large packet into several small packets, however this will be implement in QDMA driver not in Kernel DMA framework.

[Gyosun]

Hi yipingwang,

Is QDMA using the drivers/dma/fsl-qdma.c file in the LSDK20.04 folder?

I used this file before kernel 4.9, only DMA_SG was removed.

It would be nice if there was an example source code of a function similar to DMA_SG in LSDK20.04.

Thank you!

Best Regards,

Gyosun.

[yipingwang]

In LSDK 20.04, QDMA uses the drivers/dma/fsl-qdma.c file.

I discussed with the LSDK development team, there is no DMA_SG sample code in LSDK20.04.