eMMC device interface on iMX6 SABRE Smart Device board...

[EdSutter]

I'm trying to do some low level interfacing (not on linux) to the eMMC device on the SABRE Smart Board, but I'm suspicious that it may not be working.  I build/install u-boot over USB and when the target boots up, I see a few strange lines in the output...

...

Board: i.MX6Q-SABRESD: unknown-board Board: 0x63012 [POR ]

Boot Device: NOR

...

MMC:   FSL_USDHC: 0,FSL_USDHC: 1,FSL_USDHC: 2,FSL_USDHC: 3

MMC Device -1 not found

No MMC card found

...

First "unknown board", then "boot device: NOR" (there is no NOR on this board).  I just ignore them; but the

next ones imply that there's no MMC device.  I have an SD card plugged in, and the eMMC device is onboard, so shouldn't

they be found?   Gotta dig into u-boot to see if I should ignore this too; however, I figured I'd post the question here as well..

I've played with the 'mmc' command a bit, but don't really know what I'm supposed to see.  The eMMC device is mmc device 3, so I was wondering if there is any test or command I can run at u-boot to verify that this device is actually working properly.  

[RodBorras · Accepted solution]

Hi Ed,

Here are a few things you can try in u-boot (all values are always hexadecimal by default):

mmc dev <number>

On the Sabre SDB, <number> is:

  - 1 for the SD slot opposite to the power jack

  - 2 for the SD slot next to the HDMI connector

  - 3 for the on-board eMMC

mmc read <ramaddress> <sourceaddress> <blocks>

This reads the SD/eMMC and puts the result in RAM

md <ramaddress>

This shows the RAM contents

mw <ramaddress> <value> <count>

this overwrites the RAM with a given value

Example using eMMC:

mw 10800000 FFFFFFFF 100
md 10800000
mmc dev 3
mmc read 10800000 100 100
md 10800000

Try the same but with mmc dev 2, and you should be able to verify that the eMMC and SD card contents are different.

Regards,

Rod.

[EdSutter]

Rod,

Sorry for the late response got tied up with other stuff.

This is great, gives me what I need...

Thanks,

Ed