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TDA4VM: High CPU temperature frequency drop related problems

Vinter
Intellectual 400 points
Part Number: TDA4VM

Hi, ti experts,
We have the following problems with tda4vm sdk8.2 (Linux sdk & rtos sdk), please help to confirm:
1. Does the tda4vm frequency decrease when the cpu temperature is too high? At what temperature does the frequency drop?
2. Is the frequency of each core going to be reduced? For example, A72, MCU1-0, MCU12-0, MCU3-0, and so on.
3. Will reducing the frequency cause the system to stall? (Linux & rtos)?

  • 0
    TI__Guru**** 163640 points
    Vinter said:
    1. Does the tda4vm frequency decrease when the cpu temperature is too high? At what temperature does the frequency drop?

    There is NO cooling agent like cpufreq that scales the CPU frequency down.

    Vinter said:
    2. Is the frequency of each core going to be reduced? For example, A72, MCU1-0, MCU12-0, MCU3-0, and so on.

    No. This feature is not present on TDA4VM.

    Vinter said:
    Will reducing the frequency cause the system to stall? (Linux & rtos)?

    It should not. There is a thermal management guide which mostly has directions on thermal management from user space.
    This not part of SDK and this should be done additionally on top of SDK.

    https://www.ti.com/lit/pdf/spracz5

    Best Regards,
    Keerthy

  • 0 in reply to Keerthy J
    Intellectual 400 points

    Hi, Keerthy
    Thank you for your answer. One more question:
    We added thermal to Linux, so this will not reduce the thermal frequency, right?

  • 0 in reply to Vinter
    TI__Guru**** 163640 points
    Vinter said:
    We added thermal to Linux, so this will not reduce the thermal frequency, righ

    You mean Linux thermal driver for VTM? Can you elaborate on that?

    - Keerthy

  • 0 in reply to Keerthy J
    Intellectual 400 points

    Hi， Keerthy
    Yes, I think it is VTM, with the following modifications:

    device tree：Added the following modification file
    board-support/linux/arch/arm64/boot/dts/ti/k3-j721e-thermal.dtsi

    /board-support/linux/arch/arm64/boot/dts/ti/k3-j721e-mcu-wakeup.dtsi
    wkup_vtm0: wkup_vtm0@42040000 {
    compatible = "ti,j721e-vtm";
    reg = <0x0 0x42040000 0x0 0x350>,
    <0x0 0x42050000 0x0 0x350>,
    <0x0 0x43000300 0x0 0x10>;
    power-domains = <&k3_pds 154 TI_SCI_PD_EXCLUSIVE>;
    #thermal-sensor-cells = <1>;
    };

    thermal_zones: thermal-zones {
    #include "k3-j721e-thermal.dtsi"
    };

    Driver added the following files:
    linux-sdk/board-support/linux/drivers/thermal/k3_bandgap.c
    linux-sdk/board-support/linux/drivers/thermal/k3_j721e_bandgap.c

  • 0 in reply to Vinter
    Intellectual 400 points

    Hi, Keerthy
    The problem is urgent. Do you need any more information?

  • 0 in reply to Vinter
    TI__Guru**** 163640 points

    Hi,

    There are no multiple frequencies that are defined for CPU from the dts change you shared. So there is no cooling on j721e. Hence frequency should not be scaling down. The driver does introduce the thermal shutdown around 123c.

    Best Regards,

    Keerthy