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Have the DPLLJs changed between DM814x rev 2.1 and 3.0?

Stephen Turner
Genius 3476 points


Has the functionality or specs of the DPLLJs changed between DM814x silicon 2.1 and 3.0?.

I ask, because our product uses the VIDEO0 DPLLJ as a clock generator for our audio sample rate clock.  The clock rate is initialized in u-boot and then is then set/adjusted from user mode Linux using ptp system calls.

With rev 2.1 silicon, everything works as expected.  With 3.0 silicon, the DPLLJ will often lose lock when we are setting the frequency from Linux.

thanks

Steve Turner

AudioScience, Inc.

  • 0
    TI__Genius 11470 points

    Hello,

    For further details, please ask your local field engineer. Thank you.

    BR

    Vladimir

  • 0 in reply to Vladimir-XID
    Genius 3476 points

    Hi Vladimir

    There is most definately a change in the functionality of the silicon, as in our testing, we ONLY changed the DM8147 , everything else (h/w and s/w) was kept the same.  We observed this on multiple rev 3.0 silicon devices.

    That being said, we have a work around of sorts - but it does not inspire confidence.  We found if u-boot sets the same N,M,M2 as linux does on the 1st frequency set, then the PLL remains in lock.  The problem is if linux's DPLL parameter calculation algorithm ever changes and produces numbers that are out of sync with what u-boot uses, then I fear the problem will come back.

    thanks

    steve

  • 0 in reply to Stephen Turner
    Guru 10030 points

    Hi, Steve-san,

    Could you already fix this issue?

    Now we have same issue in custom board. But our OS is WEC7, not Linux.

    But its symptom is same.

    If possible, please give me some advices.

    Best regards,

    Michi