[Sugar-devel] Patch: Mobile dongles

James Cameron quozl at laptop.org
Tue Mar 27 17:28:48 EDT 2012

On Tue, Mar 27, 2012 at 10:17:16AM -0400, Paul Fox wrote:
> huh.  okay, well, 1.75 is the first of the XO models that has the
> ability to leave the USB ports powered (and i assume they all do when
> the mobile dongle is used - the hardware control is all or none).  i
> guess that driver is talking to the USB stack somehow to accomplish
> this.

interesting.  that might mean we could provide USB mouse wakeup support
on XO-1.75 by tweaking the kernel.

> next question:  is this the right behavior?  if the dongle weren't
> power cycled during resume, i guess that might be a good thing?

it is a radio and controller that associates with a radio network as
soon as it is powered.  this association requires a bit of time, of the
order of a few seconds, and some transmissions at various power levels.
once associated there's an occasional brief transmission to keep the
radio network informed; a kind of keep-alive.

the HSPA term for the association is "attached".

establishing an IP connection is a separate step.

so a power cycle increases the time taken to establish a connection, and
possibly increases the total power consumed.  on the other hand, this
has to be balanced against the power consumed while the laptop is in

the effect of a depowering on the radio network is negative but minor.
an identity slot for the device is held available until the keep-alive
is not answered.

James Cameron

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