We have a custom board with eMMC(on SD4) and SD(on SD3), when I try to boot from eMMC, it's always failed and enter serial download mode but boot success from SD.
However, I can download image to eMMC by MFGTool without any error, or access the eMMC after boot from SD.
I load my bootloader image to RAM by MFGTool and dump the SRC memory as below. Seems the system was reset by WDOG?
U-Boot > md 020d8000
020d8000: 00000521 00005860 00000011 00000000 !...`X..........
020d8010: 00000000 00000000 0000001f 12000001 ................
I think maybe timing incorrect when boot ROM try to initiate eMMC at very early stage, but how to debug this kind of issue?
Please give me an advice.