nrf5340 qspi flash dma

Question

Dear nordic engineers: 
 The only example I can find about flash is under zephyr/samples/drivers/spi_flash. However, the flash writing is pretty slow, and the MCU is halting while waiting for writing result. 
 If dma buffer is available, I can send the command to write dma data to flash and do other time consuming task. The status of the flash writing can be checked in the next MCU loop. 
 As I understand there is no dma available in any of the zephyr flash api(flash.h). Do you have examples from nordic internal? I found a post here https://devzone.nordicsemi.com/f/nordic-q-a/72045/flash-filing-system-for-nrf-connect-sdk , at least someone in nordic has aware of the useful feature (in the marked answer the config file include "help Enable support for nrfx QSPI driver with EasyDMA.") 
 If there is no available example, I would like to implement it but need some guide on how to change nrf_qspi_nor.c and nrfx_qspi and make it accessible from my main.c. Please provide some hint how I can proceed.

ovrebekk · Accepted Answer

Hi 
 szhaulai said: Hi Thanks for the answer, I got it to work with your suggestion, putting put fifo out of interrupt handler. One final question to this thread about flash driver, is it needed to erase before writing a new dataset into flash? 
 If you use the low level flash driver then you normally need to erase a page before you can write anything to it, that is correct. Since flash only allows you to clear bits when writing and not set bits any word that is not already 0xFFFFFFFF (all ones) can not be written to without first erasing the page. 
 If you use a higher level driver, like NVS, then the page erase is handled for you by the driver, and you don't need to know about the intricacies of working with flash memory. 
 szhaulai said: Some other question, is there example on using other zephyr fifo api, like k_fifo_alloc_put(). I get error on zephyr CPU and don't know how to debug. I have tried to run in debug mode, but zephyr doesn't report any error or halting. 
 Are you saying that the k_fifo_alloc_put() call doesn't return any error codes, but still the application will crash? 
 szhaulai said: I feel frustrated when it comes to zephyr, the document is not very clear. Is there forum for zephyr like the one you have hosted very well on the nordic site? 
 Zephyr is hosted on Github, which means you can raise issues or ask questions through Github directly: https://github.com/zephyrproject-rtos/zephyr/issues 
 We are also happy to help with Zephyr related questions here on the Devzone 
 Best regards Torbjørn

nrf5340 qspi flash dma

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