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SK-AM62: Boot sequence AM62x switch to Backup Boot

BO
Genius 12760 points

Part Number: SK-AM62

Customer is facing a problem with the timing of the boot sequence for their application and recognized that on the SK-AM62

We have set the BOOTMODE pins to

- SDCARD: Primary boot
- SPINOR: Backup boot

for our application.

Technically, this works fine. As soon as no SDCARD is plugged in, the U-boot is loaded from the SPI Nor.

Unfortunately the switch to the backup boot takes about 10 seconds.
This is unfortunately too slow for our application.
The idea would be to always boot from the SPI.

But for the service case it should be booted from the SDCARD, as soon as a SDCARD is plugged in to recover a possibly crashed system.

Is there a possibility to define the timeout for the backup boot or to shorten the set 10 seconds?

Regards,
Bernd

  • 0
    TI__Guru* 90745 points

    Bernd, the timeouts are in the ROM code, so there is no way to change these.  I guess i'm a little surprised that the timeout is a full 10seconds.  Can you send us the BOOTMODE pin configuration?  Did you connect the MMC1_SDCD to the card detect pin on the card cage?  When the card is not installed, is the SDCD signal high to indicate the card is not inserted?

    Regards,

    James

  • 0 in reply to JJD
    Prodigy 140 points

    Hello James

    My name is Stephan and i previously asked this question to Bernd directly.

    The Bootmode configuration is: 001101001001011
    Which should select MMC1 Primary and SPI Secondary boot:

    MMC1_SDCD is connected. Also the Level is correct according the datasheet: 1: NO SDCARD, 0 SDCARD Present.

    There is  no Clock visible on the SDCARD connector pad when the SDCARD is no populated. So i assume the romcode detects the absence of the card and does not try to boot from it.

    But anyway it takes 10 sec from powerup to SPI boot.

    I tested it with the SK.AM62x and also with our own product, which behave in the same manner.

  • 0 in reply to Stephan BAW
    TI__Guru* 90745 points

    Ok, let me check with the ROM team about the 10sec for an explanation.

    One more thing, can you dump the following register: 0x43000030  This is the what the processor latches as the bootmode.  Just want to ensure it matches your configuration you stated.

    Regards,

    James

  • 0 in reply to JJD
    Prodigy 140 points

    Hi James

    Here is the register redout from u-boot

    => md.b 0x43000030 4
    43000030: 43 1a 00 00

    Best regards

    Stephan

  • 0 in reply to Stephan BAW
    TI__Guru* 90745 points

    Stephan, ok, thanks, that looks correct .  Still waiting to hear from ROM team.

    James

  • 0 in reply to JJD
    TI__Guru* 90745 points

    The ROM team confirmed that the timeout for SD card is 10sec.  There was not a priority on timing out for SD card because it is considered mainly for development boot, not for production.  

    Is your method for boot considered for the final end product?

    Regards,

    james

  • 0 in reply to JJD
    Prodigy 140 points

    Hi James

    Yes the plan was to have this method in the final product. To be able to recover easily a broken Image in the primary boot device. Accidentially caused to an upgrade error or simmilar issue.

    According to your explanation the backup bootdevice is no realy usable for our usecase.

    Is 10 seconds timout active for all backup bootdevices or is this only valid for SDCARD?

    Is the only way to achieve another bootsource changing the Bootpins?

    Many thanks and best regeards

    Stephan

  • 0 in reply to Stephan BAW
    TI__Guru* 90745 points

    Stephan, yes i think the ROM is setup so that the most efficient way to perform a recovery boot is by changing the boot mode pins.  Each boot mode will have a different amount of timeout (the peripheral ones like USB and Ethernet will be much longer).  So the best way to setup your boot is to set the boot mode pins for your primary boot source (in your case, set SPI NOR as primary), then have a way to change boot mode pins to boot with another source (SD Card, USB DFU, etc). 

    As an example, there is only one bootmode pin difference between SPI NOR and SD Card, so you could make provisions on the board to change that one boot pin to choose the boot source during power up.

    Regards,

    James