When u-boot jump to serial downloader mode in u-boot?

[kanoumamoru]

Hello commuity,

I have one question concern with low level boot sequence.

Environment :

 - i.MX6DL @800MHz

 - DDR3 x 4pcs. (64bit bus)

 - SPI-NOR (u-boot and kernel)

 - eMMC (RootFS)

When SPI-NOR boot is selected:

  i.e. BOOT_MODE[1:0]=Internal Boot, BOOT_CFG1[7:4]=Serial ROM(SPI)

In this case, the system boot up sequence is as following :

1. ROM code copy 4K byte data (include IVT and DCD table) from
     SPI-NOR to OCRAM.
2. Init the DDR base on the DCD table settings.
3. Copy and Load the u-boot form SPI-NOR to DDR.
4. Jump to DDR to executes the u-boot.

A piece of DDR  was broken after ESD test, so DDR stress test became fail.

In other word, maybe above process 3, 4 (i.e.Copy and Load the u-boot / jump to DDR address) is not executed.

[Question]

In this case, the i.MX6 ROM BIOS will transition to the serial download mode?

Best Regards,

Kanou

[kanoumamoru]

Hi Igor,

Thank you for replying.

My customer say:

If possible, Would you tell me how serial download mode is determined by the BIOS.

What kind of logic does it change in a serial downloading mode in?

For example, jump to exception interrupt handler, DDR CRC check error, ....

Best Regards,

kanou

[igorpadykov]

Hi Kanou

yes ROM executes jump to exception interrupt handler.

Best regards
igor

[igorpadykov · Accepted solution]

Hi Kanou

you are right: in this case i.MX6 ROM BIOS will transition to the serial download mode.

Best regards
igor
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