[PATCH] huawei: treat CFUN 0 as low power state

[Ben Chan]

On Thu, May 1, 2014 at 1:15 AM, Aleksander Morgado <aleksander at aleksander.es
> wrote:

> On Wed, Apr 30, 2014 at 9:59 AM, Ben Chan <benchan at chromium.org> wrote:
> > +        /* +CFUN=0 is supported on all Huawei modems but +CFUN=4 isn't,
> > +         * thus we use +CFUN=0 to put the modem in low power state. */
> >          mm_base_modem_at_command (MM_BASE_MODEM (self),
> >                                    "+CFUN=0",
> >                                    30,
>
> Do all Huawei modems allow recovering from a +CFUN=0? i.e. will they
> still reply to AT commands in the tty after +CFUN=0 has been issued?
>
>
I can't confirm for all Huawei modems. The few Huawei dongles that I've
tested seem to allow transitions from CFUN=0 to to CFUN=1. As Huawei
suggested using +CFUN=0 instead of +CFUN=4, I'd expect their modems can
recover from CFUN=0.  If we later find some Huawei modems that fail to
recover from CFUN=0, we could specifically handle them by either
disallowing modem_power_{up,down} or see if they can support CFUN=4.
Hopefully, those are rare cases.  Newer modems are likely to support
^RFSWITCH, so we won't have a problem there.
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