On 02/14/16 09:48, Ian Smith wrote:
On Sat, 13 Feb 2016 11:17:31 -0800, Luke wrote:
  > > I searched the wiki on 'USB power' but noticed only sections 4 and 10 of
  > > https://wiki.freebsd.org/TuningPowerConsumption seemed to relate at all.
  > > If that's it or not, I'd appreciate some more guidance ..

  > That's correct, section 10 from that wiki page.
  > Here's all I did:
  > $ sudo usbconfig
  > (it then lists all USB related devices)
  > $ sudo usbconfig -d 1.3 power_save
  > (then put a device into powersave mode. I put this in a script)
  > and that was it for me. The zenbook almost imediately reports an extra
  > hour of battery and I can confirm it does indeed extend it's life to
  > close to an hour.

Ah, right.  Mine (6 uhci and 2 ehci root hubs) are all already in
pwr=SAVE mode, except for the so far unused webcam:

ugen3.2: <product 0x480c Chicony Electronics Co., Ltd.> at usbus3, cfg=0
md=HOST spd=HIGH (480Mbps) pwr=ON (100mA)

Setting that to power_save saved about 150mW, or 30mA at 5V.  Only a few
extra minutes (~2%) of battery life, but every little bit helps, thanks.

Not that that's really anything to do with the $subject ..


By default our USB stack only enables power save for USB HUBs, because it assumes that non-USB HUB device, might be broken with regard to suspend. Your findings make sense.


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