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AM4378: eMMC CRC errors

Koichiro Tashiro
Mastermind 22945 points

Part Number: AM4378

Hi,

My customer is developing their system with AM4378 and Linux.
The customer reported an issue related eMMC access error(CRC errors) on their custom board.

Please see attached excel.
Colum A to AB show command sequence when eMMC is accessed from u-boot. There is no problem.
Colum AG to BE show similar command sequence when eMMC is accessed after linux is bootup.
There are CRC errors after line#277. Responses from eMMC device have CRC errors.
eMMC_accesses.xlsx
Customer wonders why these CRC errors happen only access from linux.
Is there any points customer should check?

Thanks and regards,
Koichiro Tashiro

  • 0
    TI__Guru** 110030 points

    Hello Koichiro,

    What commands is the customer using to set up and communicate with the EMMC in Uboot and Linux? Does Linux work at lower frequencies? Maybe try the Uboot test's clock speed of 12.5MHz?

    Regards,

    Nick

  • 0 in reply to Nick Saulnier
    TI__Mastermind 22945 points

    Hi Nick,

    Thanks for your quick reply.

    >What commands is the customer using to set up and communicate with the EMMC in Uboot and Linux?

    I thought all commands are shown in the excel sheet (column E and AH).
    Is this not enough?

    >Does Linux work at lower frequencies? Maybe try the Uboot test's clock speed of 12.5MHz?

    Customer does not know how to change clock speed.
    Could you tell me how to change eMMC clock?

    SDK version is below:
    ti-processor-sdk-linux-rt-am437x-evm-03.00.00.04

    Thanks and regards,
    Koichiro Tashiro

  • 0 in reply to Koichiro Tashiro
    TI__Guru** 110030 points

    Hello Koichiro,

    Please note that Linux SDK 3.0 is too old for us to support on the forums. If I do any testing on my end, it will be with a later SDK. 

    Did the customer have to type anything into the terminal in order to send the commands in columns E and AH?

    Just to check, how is the customer measuring the clock speeds?

    You should be able to change the Linux clock speed by going to the EMMC device tree node and adding max-frequency = <12500000>; (or whatever frequency you want to test)

    Regards,

    Nick