Hi Phillipe,
The dylan branch is quite old (current is "dizzy"), and you're probably running into a bug in the boot script.
If you can use 'strings' to look at the file 6x_bootscript in the boot partition, you'll likely see something like
this:
if test "sata" = "${dtype}" ; then
setenv bootargs "$bootargs root=/dev/sda2" ;
else
setenv "bootargs $bootargs root=/dev/mmcblk0p2" ;
fi
Note the misplaced quote on line 4 above (should be after bootargs and before $bootargs).
If that's the case, replacing that boot script with the attached version will fix the issue.
This is from the "production" branch of our U-Boot tree:
u-boot-imx6/6x_bootscript-yocto.txt at production · boundarydevices/u-boot-imx6 · GitHub
You can use our on-line boot script compiler to quickly customize things if needed:
http://git.boundarydevices.com/bootscript.php