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C6748 DSP/BIOS Power Management question.

Anatoly Odler
Expert 1870 points
Other Parts Discussed in Thread: OMAP-L138

Hi,

We are developing on C6748.

There's a Power Manager feature in BIOS 5.4x for this device.

I'd like to have an idea of reliability and efficiency of this BIOS module.

  • Do you have any documented benchmarks for us regarding this feature?
  • Is it much more efficient in power consumption than the PSP's PSC module API's or it is just another way to perform the same things?

Thank you.

Anatoly.

  • 0
    TI__Mastermind 26780 points

    Anatoly,

    There aren’t any published benchmarks for PWRM on C6748 that I am aware of.  But if you are looking for expected power savings, you can gauge this largely by the device specifications.  For example, PWRM has an API that can get the device in and out of DEEPSLEEP mode easily.  Once the device is in the sleep mode, the consumption is independent of whether PWRM was used or not.  How quickly PWRM gets in and out of DEEPSLEEP does depend on the implementation.  This latency also depends upon the responsiveness of any notification clients that register with PWRM.  (At one point in time I’d done some latency cycle counts for a customer, but I’d have to search a bit to find those if you need them.)    Similarly for voltage/frequency scaling, PWRM can manage the transitions between voltage/frequency pairs, but once the app is at a given performance level, the power consumption is independent of PWRM.

    As far as comparing to PSP’s PSC module: the consumption will be the same – both PWRM and PSP provide APIs to enable and disable module clocks, and once a module state has been changed, the consumption is identical.

    There have been some power savings benchmarks done for other devices, showing power savings with certain DSP/BIOS applications.  If you haven’t seen it, an EE Times article with some measurements showing benefits:

    http://www.eetimes.com/design/signal-processing-dsp/4016979/How-to-optimize-power-consumption-in-embedded-DSP-applications-part-1

    http://www.eetimes.com/design/signal-processing-dsp/4016978/How-to-optimize-power-consumption-in-embedded-DSP-applications-part-2

    As far as reliability, the PWRM support for C6748 and OMAP-L138 has been deployed for 2+ years now.  There is one outstanding bug relating to the upwards frequency scaling logic, but this is only exposed if PWRM is used outside of the recommended configuration.  There are some high volume customers using it on OMAP-L138 with no other reported issues.  Maybe others on the forum can provide more feedback on this…

    Hope this helps…

    Regards,
    Scott