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DRA829J: Ways to boot u-boot+Linux on the A72

Stephen Turner
Genius 3476 points
Part Number: DRA829J

Hi,

Designing a system based on the DRA829J.  Not using the MCU.  Only the A72 and DSPs

Would like to boot u-boot from SPI flash, but think I see that is not possible?.  Please confirm.

I think my options for u-boot are only eMMC, SD- card and USB.  Please confirm.

Its my understanding that even though we are not using the MCU, the MCU always runs ROM code after POR and then can pass operation over to the A72 using BOOTMODE pins, correct?

thanks!

  • 0
    TI__Guru**** 163290 points
    Stephen Turner said:

    Would like to boot u-boot from SPI flash, but think I see that is not possible?.  Please confirm.

    Yes your understanding is correct. MCU R5F is the boot core so that is the starting of secondary boot loader code.

    Stephen Turner said:

    I think my options for u-boot are only eMMC, SD- card and USB.  Please confirm.

    Depends on the boot flow. SPL based boot flow supports OSPI as well + UART boot mode.
    SBL based bootflow supports SD & eMMC.

    Stephen Turner said:
    Its my understanding that even though we are not using the MCU, the MCU always runs ROM code after POR and then can pass operation over to the A72 using BOOTMODE pins, correct?

    Yes. You need to run either RTOS based SBL or U-Boot based SPL on MCU R5F to load ATF/SPL and start A72.

    Best Regards,
    Keerthy

  • 0 in reply to Keerthy J
    Genius 3476 points

    Hi Keerthy,

    Thanks for your reply.  Just to clarify my thinking, we could do the following:

    1. Set MCU to boot from OSPI and ARM to boot from eMMC

    2. MCU would boot R5 u-boot from OSPI.  This would setup peripherals, LPDDR4, load A72 u-boot from eMMC and pass control to the ARM?

    3. u-boot running on the ARM would load the Linux kernel from eMMC.

    thanks

  • 0 in reply to Stephen Turner
    TI__Guru**** 163290 points
    Stephen Turner said:

    1. Set MCU to boot from OSPI and ARM to boot from eMMC

    2. MCU would boot R5 u-boot from OSPI.  This would setup peripherals, LPDDR4, load A72 u-boot from eMMC and pass control to the ARM?

    3. u-boot running on the ARM would load the Linux kernel from eMMC.

    Stephen,

    This is not supported. What we support is r5 SPL & A72 SPL & U-Boot.img in OSPI. So basically all the bootloaders are loaded from the same boot media.
    Its based on the dip switch settings.

    That said A72 U-boot can load the kernel from any boot media. For ex: eMMC that you want. So this what is supported in the default SDK.
    The other option that I can recommend is all the bootloaders in eMMC. That is a supported combination.

    - Keerthy