i.MX8 DualXPlus-Flex SPI interface with OCTAL SPI Flash

[kailas_kharse]

Hello Team,

We are developing a custom board where we want to use OSPI Flash and OSPI RAM interfaced via Flex SPI.

We are considering the following use case:

"OSPI Flash Memory" shall be used for booting, and the boot images will be loaded to "OSPI RAM" without using LPDDR4 RAM. "OSPI Flash memory" will be only used for loading the boot images to "OSPI RAM"  and after the boot images are loaded to OSPI RAM, we will execute all operations from OSPI RAM, OSPI Flash Shall not be used.

So, Is it possible to do this?
If Yes, please let us know more detail about it.

[igorpadykov]

Hi Kailas

only one octal device can be used, may be useful to look at flexspi_octal_polling_transfer.c

example in SDK_MEK-MIMX8QX Welcome | MCUXpresso SDK Builder 

Best regards
igor
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[kailas_kharse]

Thanks Igor,

I believe changes need to be implemented in U-boot, As I.MX8 DualXPlus supports only single Octal Memory for interfacing, How can Images be transferred from Octal ROM to Octal RAM if we have not interfaced any other Memory (eMMC and LPDDR4). Will it be possible to communicate in 8-bit mode for both (OCTAL RAM and OCTAL ROM) memories simultaneously.

I did not understand how this can be made possible. Can you please guide on above scenario so it can be helpful for me to understand this implementation.

Thanks,
Kailas K.

[igorpadykov]

Hi Kailas

you are right, only one Octal device can be connected, not both simultaneously.

Best regards
igor

[kailas_kharse]

Thanks, Igor for confirming.

With reference to the initial query response from you, I want to understand,

How can I load the images from Octal ROM to Octal RAM using single Flex SPI which supports only single OCTAL Interface?

Here we are not interfacing any other memory ( LPDDR or EMMC are not connected) to i.Mx8dualxplus.

The simple goal is to use i.mx8dualxplus along with Octal ROM and Octal RAM. How this Use case can be implemented. ( Load images from Octal ROM to Octal RAM and further execution will be done in Octal RAM).

What are the changes I need to do in U-boot?

Do you see any Challenges in this implementation? if Yes, What can be those challenges?
Do you have any references for this implementation?

Regards,

Kailas K.

[igorpadykov]

Hi Kailas

>How can I load the images from Octal ROM to Octal RAM using single Flex SPI which

>supports only single OCTAL Interface?

seems this is not feasible, only one Octal device can be connected, not both simultaneously.

Best regards
igor

[bimal]

Hi Igor,

If we use an external FlexSPI Bus Multiplexer to interface Octal Flash and Octal RAM. Than is it possible to do the above operation by multiplexing it on single Flex SPI bus?

(Here still both memory will not be simultaneously used but required to do time multiplexing )

[igorpadykov]

Hi Bimal

yes, I believe it is possible with external multiplexer.

Best regards
igor

[bimal]

Hi Igor,

Can you let us know what should be done in software /firmware if we are going to interface octal flash and octal ram through external multiplexer.

- How to achieve the use case mention above by using external mutliplexer?

- Is there any similar use case performed in processor? if yes what kind of support we can get to achieve the same?

- How frequent the switching between Octal flash and octal RAM will be required? (So that we can select the multiplexer accordingly)

[kailas_kharse]

Hello Igor,

If it can be made possible using a multiplexer, Where the changes need to be done in U-Boot/ SCFW provided by NXP?

Does SCFW support the above feature or does SCFW need modification from NXP to support loading OSPI Flash to OSPI RAM using external Multiplexer?

What are the challenges do you see if we follow the above approach mentioned by Bimal?

Thanks & Regards,

Kailas K.

[kailas_kharse]

Thanks, Igor for Confirming.

Regards,

Kailas Kharse