TDA4AL-Q1: How do I turn off DMA after linux starts？

Hi,

Our expert is out of office on year-end vacation. Please expect a delay in responses.

Regards,

Josiitaa

li liu said:

After booting linux using emmc boot0, we find that the read and write rate of linux is slow. We suspect that it is caused by DMA. Is the read and write rate of linux related to DMA? How do I turn off DMA after Linux starts?

When you say Read/Write is slow is it eMMC read/write? If yes then eMMC does not use the UDMA(System DMA).

- Keerthy

Hi Keerthy,

   Yes,it is EMMC read/write.When using sd card, spl boot mode. The read/write rate for emmc is 40Mb/s when DMA is on, and 6.9Mb/s when DMA is off. It can be seen that DMA has an impact on emmc read and write.

   We need DMA when our system starts, how to turn on DMA after linux starts?

li liu

Hi,Keerthy

Emmc boot0 linux can't get up before this patch is added, but linux can get up after this patch is added. However, the emmc read/write rate slows down.

li liu

Hi Liu,

Is this a custom board? If yes which eMMC part are you using?

Also please share the failing logs.

Best Regards,

Keerthy 

Hi Liu 

Performance will degrade as you are disabling the SDMA/ADMA in the host controller also you are disabling the Command que capability on the emmc device.

li liu said:

Emmc boot0 linux can't get up before this patch is added, b

What was the error you were getting without the PATCH ?

Regards
Diwakar

Hi,

When I don't apply patch, the error log is as follows. I can only provide screenshots for now.

I am trying to reproduce the problem, and I will add the log later.

li liu