GSM call during suspend

Mark Brown broonie at
Fri Mar 27 20:18:23 CET 2009

On Fri, Mar 27, 2009 at 05:41:39PM +0100, Michael Trimarchi wrote:

> I will start to write and test some code for avoid suspend of dac during  
> GSM call,
> I think that it can be possibile. There are two possible approch:

This is a substantial task which needs to be done at at least the
subsystem level rather than in the individual drivers.

> I would like to avoid a modification to the wm8753.c file and maybe it  
> is possible to
> overwrite the suspend and resume call, and call the oldone only if the  
> call is not active.

This needs to be done at least at the subsystem level, apart from
anything else you need to avoid powering down external components like
the headphone amplifier if they are active.  You also need to handle the
bluetooth subsystem, ensuring that if the audio is routed via that.
Ideally there would be a kernel wide interface for user space to use to
control this functionality.

> Android can use this feature when the user made a long call the cpu can  
> be swithed off (the resume
> time is short, about ~1 second). What do you think about it?

Ideally the Android developers would be engaging with the kernel
community as a whole on this.  Unfortuantely the G1 has the audio
offloaded to a DSP which functions independantly of the main processor
so this has not been an issue for them.

More information about the openmoko-kernel mailing list