Power Saving modes on BBB?

Paolo Pisati paolo.pisati at canonical.com
Thu Jul 30 08:35:25 UTC 2015

On Thu, Jul 30, 2015 at 09:45:25AM +0200, Gábor Paller wrote:
>    Am I right that the entire cpufreq subsystem is also disfunctional on
>    Snappy BBB?
>    Snappy consumes 40% more current on idle prompt (boot completed, no user
>    task is running) than the baseline TI SDK and I can't find the frequency
>    scaling files under /sys.

ubuntu at beaglebone:~$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors 
conservative ondemand userspace powersave performance 

About the 40% more consumption, how did you get that number? same cpufreq
governor? same config?

>    Also, bizarrely, if the BBB is entirely shut down, Snappy still consumes
>    around 120 mA while TI SDK goes down to almost 0.
>    This, along with the lack of power-saving modes is pretty much a
>    showstopper for any serious battery-operated application on Snappy.

But yes, the TI BSP kernel is ahead in terms of support wrt power savings on the
beeaglebone (after all it's their SOC and that's kernel they develop against...)
compared to upstream (and that's the upstream that we track) - since you are so
interested in the TI kernel and no one has done it yet, would you consider packaging
it and releasing for the community as a kernel snap?

I think Olivier or Ricardo can point you to the latest document
showing how to do that

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