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We have beaglebone black based custom board with 512MB RAM and 4GB eMMC.

I was trying to read CSD register from the board however I am getting following error.

# mmc csd read /dev/mmcblk0
MMC/SD information directory '/dev/mmcblk0' does not exist.

When I checked the mmc csd command's help it says "device path should specify the csd file directory.

# mmc csd --help
Usage:
        mmc csd read <device path>
                Print CSD data from <device path>.
                The device path should specify the csd file directory.

So I tried below command as well,

mmc csd read /sys/class/mmc_host/mmc1/mmc1\:0001/csd

However it doesn't work. I don't know what should be passed as path spec. I know i can read that sysfs file to get csd value, however i thought mmc-utils should parse it and display.

I am will look at mmc-utils code and update my findings here. meanwhile anyone knows let me know so that it is faster.

ART
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2 Answers2

5

Assuming the path is correct, it should work if you remove the trailing csd from the path:

mmc csd read /sys/class/mmc_host/mmc1/mmc1\:0001/
1

Alternatively:

mmc extcsd read /dev/mmcblk0
peterh
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Gerbrand Visscher
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