IMX6ULL's EMMC Boot Issue: Success with SD, Failure with EMMC - Help Wanted!

[CaptainMat]

Hi,

I'm facing an issue with our custom IMX6ULL boards where booting from the EMMC is not possible. Although the EMMC appears to be programmed correctly, it simply won't boot. However, there are no problems programming and booting from an SD card. After conducting X-ray examinations, soldering doesn't seem to be causing the issue.

Interestingly, I discovered a workaround to make the boards boot. After initially programming the EMMC (which doesn't boot by itself), I directly program the U-Boot to DDR3. Then, I access the U-Boot terminal via UART1, and by entering the "boot" command, the system boots up successfully! Despite this, the board still refuses to boot independently.

I have 16 boards:

1x EMMC programs ANDS boots (??!) ==> mysteriously one boards does indeed boot

2x EMMC does not program at all

13x EMMC programs but does not boot.

My boot settings:

BOOT_CFG1=0111 0000

BOOT_CFG2=0100 1100

I also read the bootlog via Segger J-link JTAG mem tool. It says first "Reading data from boot device fails" and on next try "The boot device initialization fails" before going back into serial downloader mode

Attached is relevant schematic. ANY help would be greatly appreciated !!!

[CaptainMat]

Hi, thanks a lot for the reply! 

I measured the boot settings, they were the same as in your example.

However, I figured out if I put BOOT_CHF1[4] = 0, AKA if I put to "normal boot", this restores the boards, and they boot on the EMMC. This is only for the boards that we are able to program to begin with. It does not restore the units where programming of the EMMC is entirely impossible (10% of units).

Do you guys know what the reason behind this might be? Nor your boards, nor the reference design (EVK) had this bit low.

I want to gain some confidence that I fixed the issue.

[Chavira]

Hi @CaptainMat!

That is strange.

Could you please share your entire schematic?

What is the process to flash your emmc?

Please check the hardware design user guide for iMX6ULL to discard another anomaly in your design.

If you can't publish your schematic, please open a private case following the link and we will review your schematic and probably we can give you a solution.

Support | NXP Semiconductors

[CaptainMat]

Thanks,

I launched a private support topic. I will report back to this topic once I figure out the issue for the benefit of the wider audience. 

[Chavira]

Thank you for contacting NXP Support!

I can see your connections are the same as the EVK.

Please try the configurations like the evk (See the attached Image)

If you can't boot with that configuration, please try flashing your board using the UUU utility If you can boot from JTAG I think is only configurations or bad flashing.