I have a custom board which is based on i.MX6UL CPU. It has eMMC on it but I can not flash it.
For testing purposes I simplified ucl2.xml like;
<LIST name="eMMC" desc="Choose eMMC as media">
<CMD state="BootStrap" type="boot" body="BootStrap" file ="firmware/u-boot-imx6ulevk_sd.imx" ifdev="MX6UL">Loading U-boot.emmc</CMD>
<CMD state="BootStrap" type="jump" > Jumping to OS image.emmc </CMD>
I also modified the content of "mfgtool2-yocto-mx-evk-sdcard-sd2.vbs", SDCard to eMMC.
When I run this script, there is no debug output on UART.
But same simplification works for IMX6ULEVK even there is no SD card on it and I can see some outputs.
Between, on my board DDR test tool is able to work, I can do DDR stress tests. But it passes under the frequencies of 300MHz because my DDR routing has some length equalization problems.
I think this does not make any sense as this initial bootstrapping does not use ram.
So the questions are;
Is my assumption for ram usage in initial bootstrapping operation correct?
eMMC on the board has no function at this stage, right?
CPU works well as it can run ddr test software which means it has right voltage levels and clock source. Is that right?
So why this board does not work? Any idea?
Thanks and have a nice day..