Reload BOOT_MODE from UBoot

[kevinjoly]

Hello,

I am using Uboot on an i.MX6UL. I'm flashing UBoot from the "serial downloader" mode (BOOT_MODE = 01). Once the flashing is finished, I would like to reset the CPU in order to boot properly from the eMMC. The problem is, when I type the reset command from Uboot, the BOOT_MODE bits from SRC_SBMR2 are still 01 even if the BOOT_MODE pins are 10. Thus, the CPU boot a second time in "serial downloader" configuration instead of "internal boot".

I was wondering if forcing a new latch on BOOT_MODE pin was possible. If yes, how to do it?

Thanking you by advance.

Regards,

[igorpadykov]

Hi kevinjoly

is it working after por or switching power off/on, as uboot may use own reset routines as described on

u-boot-acadia1.0-beta/0404-ENGR00163513-MX6Q-UBOOT-Add-download_mode-cmd.patch at master · linksprit... 

issue may be posted on uboot mail list

U-Boot Info Page 

alternatively one can try with sdk using wdog reset

Github SDK
https://github.com/backenklee/swp-report/tree/master/iMX6_Platform_SDK

Best regards
igor
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[kevinjoly]

Hi Igor.

Indeed, in Uboot the reset sequence is done by a watchdog u-boot/imx_watchdog.c at master · u-boot/u-boot · GitHub .

I tried to implement something like the patch you mentionned. Unfortunately, since the BOOT_MODE pin are used, the GPR9 (copied to SBMR1) is not taken in account (correct me if I'm wrong). However, the patch you mentionned is aimed for iMX6 (not iMX6UL).

Is it the same ROM code ? Where can I find documentation about GPRn register usage in the ROM code?

Best regards,

Kevin

[igorpadykov]

Hi Kevin

is it working with por or some sdk example, without GPR9 usage.

Best regards
igor

[kevinjoly]

The boot mode is correct on power on reset. For instance, if the boot mode is serial downloader and I reset the chip with the internal boot mode selected, internal boot is choosen. That is not the case in watchdog reset.

Didn't try with SDK.

[damiendejean]

Hi kevinjoly,

I'm facing the same issue on an imx6q, did you solved your problem ? How ?

Best regards,

Damien.

[kevinjoly]

Hi Damien,

Yes, the problem was that the watchdog output pin wasn't connected to the reset chip.

Cheers

Kevin