U-boot stucking without going to OS

[hamze60]

Hello,
I have a design with old but cheap Allwinner A20 processor. At the boot time, u-boot keeps rebooting just after reaching the below line (just after DRAM: 1GiB):

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U-Boot SPL 2019.07 (Oct 13 2020 - 17:36:08 +0300)
DRAM: 1024 MiB
CPU: 912000000Hz, AXI/AHB/APB: 3/2/2
Trying to boot from MMC1 

U-Boot 2019.07 (Oct 13 2020 - 17:36:08 +0300) Allwinner Technology
CPU:   Allwinner A20 (SUN7I)
Model: Olimex A20-OLinuXino-LIME2-eMMC
I2C:   ready
DRAM:  1 GiB
I even tried ready images from internet, alghtough some did not reboot countinlusly, but they stuck at the same place (line: DRAM:  1 GiB). BTW, in our PCB, we did not use "SD card detect" mechanical pin, so I already changed the U-boot CONFIG_MMC0_CD_PIN="PH1" to ="" before compile (otherwise it stuck in u-boot SPL and even did not go to u-boot). I treid to play with U-boot settings to have debugging message, but nothing changed. Can anyone give a clue? can the problem be a hardware issue? On internet I saw that I should see something like this, after DRAM line:

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.....
I2C:   ready
DRAM:  1 GiB
MMC:   SUNXI SD/MMC: 0
In:    serial
....



Thank you

[LubOlimex]

Honestly it seems like a powering issue. Try a more powerful power supply (more current at same voltage). If the problem remains probably check your power wires width and power circuit (if it is your own design, as I understand it).

[hamze60]

Yes, you are right! we've already had problem with A20's recommended power manager chip, and had many modifications on PCB. I tried to make DDR power source independent from power manager, and feed it directly from another LDO and now it passed that line!
Thanks for your valuable comment.