[2008.8] TangoGPS/gpsd and suspend/resume
cedric.berger74 at gmail.com
Mon Sep 15 14:03:11 CEST 2008
On Mon, Sep 15, 2008 at 01:20, Mike (mwester) <mwester at dls.net> wrote:
> Radek Bartoň wrote:
>> Hi all.
>> Is GPS supposed to work after suspend wake up?
> I guess that's a matter of one's expectations; I can see strong
> arguments that would say that GPS should not be suspended in the first
> place (i.e. the GPS chip should remain running while the host CPU is
> suspended, so that it can keep track of where we've been). The counter
> to that argument is a technical one -- the GPS units can't keep their
> own log info, so the host CPU needs to stay running in the first place
> if you want the GPS to keep track of where one has been continuously,
> and that therefore if userspace lets the host cpu suspend then it might
> as well shut off the GPS too.
> The way it works in the kernel is the latter assumption: power to the
> GPS is turned off on suspend, and remains off (regardless of original
> state) on resume. It is left to user-space to re-initialize the GPS on
> resume, if a user-space application wishes to, but the primary
> assumption is that if you want the GPS to stay running, don't let the
> device suspend in the first place.
And I guess turning off GPS during suspend will reset GPS state and
need another cold restart (since GPS chip has no memory) ? So getting
a new fix would be long (at best)...
If so, it is indeed a strong argument not to turn off gps.
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