We use our own custom designed board that include The iMX6D ,based on the SabreSD example.
We run on it Yocto 1.8 with BSP version 3.14.52 .
We use SD2 port for WIFI communication, SD3 for SD slot and SD4 for eMMC.
The system is working good with one problem:
If you insert an SD card while the system is running it cause the system, to crash with out errors.
I am pretty sure it is Hardware problem.
I did several tests, one of them was to check if it happening in the "u-boot" too and it does.
One more thing it is that it doesn't happens with all SD cards.
I can't tell why but it usually happening with the faster SD cards.
I have compared it with the Wanboard I have loaded both of them in to "U-Boot". Then inserted a problematic SD card. The Wandboard worked perfect while my custom board crashed.
I looked for differences in the designs:
1. In my design I don't use 33 ohm resistor in series on the clock line.
2. The Wandboard design use SD2 while I use SD3 in my design.