[Gta04-owner] Linux 3.7 for gta04.

Lukas Märdian luk at slyon.de
Fri Feb 15 11:21:19 CET 2013


Am 14.02.2013 00:39, schrieb NeilBrown:
>> I started playing with 3.7 recently.
>> But now I've got a problem: after trying to suspend my GTA04 (echo mem >
>> /sys/power/state) it resumes directly afterwards.
>>
>> At first I thought it would be the GPS (as it was on older kernels), but
>> this shouldn't be a problem anymore on 3.7.. But I'm not sure how to
>> prove this, as when I open /dev/ttyO1 GPS is powered on automatically.
>> Is there a way to check (and/or force) the GPS power state?
> 
> The kernel driver which manages the GPS state is rather noisy still.
> When it pulls the power-toggle down it prints
>    GPS down
> when it pulls it back up it prints
>    GPS up
> A little later it prints
>    GPS idle
> 
> meaning that it has waited 10msec, so the GPS should have noticed the 'up'
> transition.
> 
> This sequence should toggle the power state (on->off or off->on).
> 
> Whenever the GPS sends a character while it 'should' be off, the driver will
> print a single "!".  No newline, so you might get several of these on a line.
> 
> When anything opens /dev/ttyO1, it prints:
>    GPS SET to 1
> When it is closed of the last time, or when the system suspends even if the
> device is open, it prints
>    GPS SET to 0
> 
> So if the last GPS SET message  is GPS SET to 0, and there are no '!'
> messages, then you know that the GPS is off and should be off.

Thank you. This sounds reasonable, so I can check if GPS is on or off.

>> Or is there in general any way in Linux how to determine which interrupt
>> triggered the resume, like a list of the last interrupts in order of
>> occurrence?
> 
> Not really.  You sometimes get a "last active wakeup source" message, like
> 
> [ 1156.672058] last active wakeup source: twl4030_pwrbutton
> 
> It is certainly worth checking for that.  You might need a CONFIG option to enable it.
> 
> I would compile with
> 
> CONFIG_PM_DEBUG=y
> CONFIG_PM_ADVANCED_DEBUG=y
> CONFIG_PM_SLEEP_DEBUG=y

Ok, nice hint. I'll try with these options enabled.

Regards,
  Lukas


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