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Powering down the DSP in DM6467

Mohammed Anwar
Prodigy 140 points
Other Parts Discussed in Thread: OMAP-L138

Hi,

I am working on the power management feature of DM6467.

The DSP Bios version is 5.41.00.06

My query is

1) Does the above DSP bios mentioned above support low power mode. ie does the DSP enter low power mode when idling.

2) Is it possible to know on the ARM side that the DSP is idling and hence it clocks can be turned off?

3) As per the documention to put the C64+ DSP clocks can be turned off via ARM core using the associated mode control registers(LPSC).

Regards

Mohammed Anwar

 

  • 0
    TI__Expert 8260 points

    Mohamed,

    1> I will check out DSP Bios experts and get back to you.

    2> There is no way ARM can know that DSP is in IDLE state because ARM can't see DSP internal registers.

    3> When ever you want to turn off DSP clocks, it can be done from ARM side by following the sequence mentioned in "OMAP-L138 Applications Processor System Reference Guide (http://www.ti.com/litv/pdf/sprugm7d)" in Section 10.7.4.1 C674x Megamodule Clock OFF (page 149). The same sequence applies for DM6467 also.

    The corresponding DM6467 steps are mentioned in "TMS320DM646x DMSoC ARM Subsystem Reference Guide (http://www.ti.com/litv/pdf/spruep9e)" Section 12.5.2.2 DSP Module Clock Off (Disable) (Page 128). This section is missing few steps that are there in http://www.ti.com/litv/pdf/sprugm7d. The missing steps will be added in the next revision of DM6467 ARM Subsystem User's Guide. Bottom line is:

    Before running clock disbale sequence on ARM side:

    a> Enable power-down controller interrupt PDC_INT (DSP interrupt #118) on DSP side.

    b> Have PDC_INT ISR that sets PDCCMD register and executes the IDLE instruction.

    Regards, Srirami.

  • 0 in reply to srirami
    TI__Mastermind 26780 points

    Mohammed,

    Regarding #1: No, DSP/BIOS does *not* provide power management support for the DM6467 device.  There is power management support in BIOS 5.41 for other devices, but not for the DM6467.

    Regards,
    Scott