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AM5728: Register configuration for AVS

Guru 10235 points
Part Number: AM5728
Other Parts Discussed in Thread: TPS659037

Hello, TI Experts,

 

Our customer sent us some questions about Adaptive Voltage Scaling(AVS) of AM5728.

 

Our understanding is as follows;

1:From DataSheet(SPRS953B) "5.5.1 AVS and ABB Requirements"

  - For using AM5728 device, AM5728 register configuration for AVS Voltage setting is Mandatory.

2:From TRM(SPRUHZ6H) "18.4.6.12 AVS Class 0 Associated Registers"

  - AM5728 register configuration for AVS Voltage setting is needed once enough after booting.

 

Is this understanding correct?

And If there are some way or related documents of "not using AVS", please also tell us.

Best regards

  • The PM experts have been notified. They will respond here.
  • matusan said:

    1:From DataSheet(SPRS953B) "5.5.1 AVS and ABB Requirements"

      - For using AM5728 device, AM5728 register configuration for AVS Voltage setting is Mandatory.

    Yes. See AM572x datasheet, section 5.5.2 Voltage And Core Clock Specifications
    (4) For all OPPs, AVS must be enabled to avoid impact on device reliability, lifetime POH (Power on Hour), and device power.

    matusan said:

    2:From TRM(SPRUHZ6H) "18.4.6.12 AVS Class 0 Associated Registers"

      - AM5728 register configuration for AVS Voltage setting is needed once enough after booting.



    If you will not change any frequency/OPP after booting (and the system is configured to not change frequency/OPP) then yes, the configuration in u-boot is once and enough.

    If you change any frequency/OPP after booting (or the system change it), then the procedure will start again and again, see the below wiki page for more info:

    http://processors.wiki.ti.com/index.php/Linux_Core_Power_Management_User's_Guide_%28v4.4%29#Power_Management_on_DRA7_platform

    Regards,
    Pavel

  • Note that AM57x linux is configured with ondemand governor enabled by default. Which means AM57x Cortex-A15 MPU frequency/OPP will change automatically based on load, will switch between OPP_NOM and OPP_OD. This switch will initiate the AVS procedure to start.
  • Hello

     

    Thank you for your detailed explanation.

    I really appreciate your help.

     

    Our customer sent us some additional questions with AM5728 and PMIC(TPS659037).

    Question:

       If we will not change any frequency/OPP after booting,  which registers of PMIC are needed to configure?

     

    They would like to know the register configuration sequence/procedure to PMIC(TPS659037) registers by AM5728. 

    If there are some way or related documents of recommendation for PMIC registers configuration sequence/procedure with AM572x, please tell us.

     

    Best regards

  • matusan said:
       If we will not change any frequency/OPP after booting,  which registers of PMIC are needed to configure?

    Do you need to configure PMIC registers after booting (at user space level)? If yes, why?

    If you will not change any frequency/OPP after booting (at user space level), there is no need to configure PMIC registers after booting (at user space level).

    matusan said:

    They would like to know the register configuration sequence/procedure to PMIC(TPS659037) registers by AM5728

    If there are some way or related documents of recommendation for PMIC registers configuration sequence/procedure with AM572x, please tell us.

    See the below links:

    Regards,
    Pavel

  • Hello,

    Thank you for your kindness.
    I really appreciate your help.

    Our customer product is designed with 3rd-party OS (commercial RTOS).
    (They don't use TI-Processor SDK.)

    So it seems they consider AVS-realize-options including additional software development(SW-dev.) impact as below.
    - option1: Once PMIC register-initialize configuration is done, PMIC registers are never changed.
    -> They cannot use AVS. But SW-dev. impact seems to be low.
    - option2: Develop additional software for AVS.
    -> They can use AVS. But SW-dev. impact seems to be high.

    From those background, based on your information, we will answer to the customer as below;
    - If you will not change any frequency/OPP after booting, there is no need to configure PMIC registers after booting.
    -> Answer for option1
    (If you have additional explanation for "at user space level" from the point of 3rd-party OS, please tell us.)
    - Related documents for PMIC register configurations as below;
    - www.ti.com/.../sliu011d.pdf
    - also see TPS659037 Register Map (sliu015.pdf)
    from www.ti.com/.../technicaldocuments

    We would like to provide some clues for both "not using AVS" and "PMIC registers configuration from PMIC web site".
    If you have any comment or recommendation, also please tell us.

    Best regards
  • matusan said:
    Our customer product is designed with 3rd-party OS (commercial RTOS).

    For software related questions, you should contact the RTOS provider. We can help you regarding hardware questions and TI SW related questions.

    matusan said:
    (If you have additional explanation for "at user space level" from the point of 3rd-party OS, please tell us.)

    User space is after booting, when system is up and running, and applications are running.

    Before booting the system is power off.

    During booting we have u-boot and linux kernel loading.

    Regards,
    Pavel

     

  • Hello,

     

    Thank you for your kindness.

    I really appreciate your help.

     

    You are right.

    I understand what you mean.

     

    Best regards