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How to make work (M)DMA pool in SRAM on custom SOM with STM32MP151/7C

DamH1
Associate

We try to configure the (M)DMA in Linux device-tree for our System on Module board based on STM32MP151/7C but it always said us that it cannot configure it so we had to disable dma for memory (QSPI Nor/NAND and FMC Nand) which cause performance issue.

If we do not set

  /delete-property/dmas;

/delete-property/dma-names;

in device-tree for qspi, the qspi try to use DMA and do not detect chip on the bus.... (there no more logs for qspi in dmesg).

Here are the logs I have at Linux kernel boot :

[   0.424027] stm32-dma 48000000.dma-controller: no dma pool: can't use MDMA: 0

[   0.425335] stm32-dma 48000000.dma-controller: STM32 DMA driver registered

[   0.425784] stm32-dma 48001000.dma-controller: no dma pool: can't use MDMA: 0

[   0.427082] stm32-dma 48001000.dma-controller: STM32 DMA driver registered

How can I configure correctly the DMA pool ?

N.B: We also use OPTEE which is located in SRAM too but the two memory reservation are not overlapped so I do not understand why it does not want to be initialized.

What can be the correct dma-pool configuration for dma to work as expected ?

1 REPLY 1
Douglas MILLER
ST Employee

This forum thread was marked by the moderator as needing a little more investigation, so a Support case was created in your name and will be handled off-line. Should anyone have any similar questions, please feel free to open a Support case directly at your myST portal at https://community.st.com/s/onlinesupport