topic When u-boot jump to serial downloader mode in u-boot? in i.MX Processors

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

kanoumamoru — Sun, 28 Aug 2016 09:19:41 GMT

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 :

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

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

igorpadykov — Sun, 28 Aug 2016 23:23:30 GMT

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

kanoumamoru — Mon, 29 Aug 2016 04:32:40 GMT

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

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

igorpadykov — Mon, 29 Aug 2016 05:32:33 GMT

Hi Kanou

yes ROM executes jump to exception interrupt handler.

Best regards
igor