Is it necessary to disable modem before powering it down?

[Thieu Le]

In this particular case, the command AT%DPDNACT=0 took longer than 10s,
which is too long when the user suspends the system.

Thanks, I'll take a look at the internal states and see if we can reset it
without going through a full disable.



On Wed, Feb 19, 2014 at 4:48 PM, Dan Williams <dcbw at redhat.com> wrote:

> On Wed, 2014-02-19 at 14:21 -0800, Thieu Le wrote:
> > Hello,
> >
> > I am trying to solve a problem during our system suspend where the
> disable
> > modem step takes a long time and it would be quicker to just go straight
> to
> > modem power down.
> >
> > mm-iface-modem.c:handle_set_power_state_auth_ready() checks to make sure
> > the modem is disabled before allowing it to be powered down.  Is this
> done
> > because some modems require it to be in a disabled state before allowing
> > the power down?
>
> Out of curiosity, which command takes too long?
>
> I think this is done mostly to ensure that internal stuff is cleaned up
> correctly; like timeouts, polling the modem for status, and other things
> that may have been set up during the enable state.  I don't think most
> modems would care about being disabled if you're just going to CFUN=0
> them.
>
> If we were able to ensure that these things were properly cleaned up,
> then we could jump directly to the power down state.  The way to do that
> would probably be to identify what gets torn down during 'disable',
> split that out into separate functions that could be called from both
> disable and power down, and then do that from both places.
>
> Dan
>
>
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