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TDA4VM: Is it possible to boot from sd while sd inserted and boot from emmc if sd is not inserted after power on ?

Veitch Kyrie
Intellectual 500 points
Part Number: TDA4VM

Hi TI,

Normally our custom board boots from emmc, but in case emmc carshes somehow, it can still boot from sd without changing the dip switch on hardware,  thus is it possible to boot from sd while sd inserted and boot from emmc if sd is not inserted? thanks!

  • 0
    TI__Mastermind 42135 points

    Hi,

    Sorry, I am a little confused here. Can you please elaborate what is your primary boot mode here? Do you want to boot primarily from SD and keep eMMC as backup or you want to boot from primarily eMMC and keep SD as backup.

    You can keep eMMC as primary boot mode and SD as secondary boot mode by changing the boot switch configurations.

    This will choose the SD as a backup boot mode if any failure happens while booting from eMMC at ROM execution stage. But in case any failure happens once the SBL is loaded, then choosing the SD as backup mode has to be taken care by SBL.

    But using eMMC as backup mode is not supported by the hardware. This has to be totally handled in the application.

    Regards,
    Parth

  • 0 in reply to Parth Nagpal
    Intellectual 500 points

    Hi Parth,

    Parth Nagpal said:
    Do you want to boot primarily from SD and keep eMMC as backup or you want to boot from primarily eMMC and keep SD as backup.

    we want to keep SD as backup.

    Parth Nagpal said:
    But in case any failure happens once the SBL is loaded, then choosing the SD as backup mode has to be taken care by SBL.

    could you please describe more specifically at this point? because I am very clear about what to do with SBL if keep SD as backup, thanks

  • 0 in reply to Veitch Kyrie
    TI__Mastermind 42135 points

    Hi Veitch,


    If you want to keep SD as a backup mode you can use the configurations mentioned previously. When you select SD card as backup mode using the above configuration, the ROM will first look for a valid image in eMMC and if ROM does not find a valid image in eMMC it look for it in SD.


    But in case ROM does find a valid boot image (SBL) in eMMC and the control is transferred to SBL, then SBL needs to take care of booting from SD in case of failure. This feature is not supported out of box by SBL, so you have to modify the SBL to detect the failure and take necessary action depending on the nature of failure.

    Regards,
    Parth