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How to Create MicroSd Image for IMX28 (Yocto)

Question asked by Peter Sinka on Feb 11, 2014



We have some custom hardware which has a 4-bit wide MicroSD card instead of an 8-bit wide SD card. I can build an Imx28-EVK image (core-image-lsb-dev) and have it boot up fine on the imx28-evk hardware.

I'm using the 3.12 kernel provided by linux-fslc


When I change to our custom hardware I change the .dts file to reflect the 4-bit interface instead,


pinctrl-0 = <&mmc0_4bit_pins_a 

  &mmc0_cd_cfg &mmc0_sck_cfg>;

bus-width = <4>;


The hardware is connected correctly for this pinout.


Now when I power up the card, u-boot loads fine but it hangs at this point:


Waiting for root device /dev/mmcblk0p3...


Looking at the partitions from my Ubuntu machine, I can see that the rootfs is indeed located at /dev/mmcblk0p3, but it just doesn't seem to be loading.


I found this thread, but it doesn't help me


I'm not experienced with embedded linux systems, or yocto, or u-boot command line so if the answer is "all you need to do is modify u-boot" I'm going to need a little more guidance than that. I've attached the output of the serial console on boot if that helps?


Edit: I should also say that I'm not ruling out a hardware issue, it could be that everything is hunky dory (dora) and the sd card is browning out, I will investigate this in the meantime.



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