[Tinyos-devel] Msp430RefVoltArbiterImplP.nc switchOff loop

[Philip Levis]

On Apr 4, 2007, at 8:37 AM, Maxime Muller - s h o c k f i s h / wrote:

> Hi all,
>
> On tos 2.x, file $TOSDIR/chips/msp430/adc12/ 
> Msp430RefVoltArbiterImplP.nc
> during event void AdcResource.granted[uint8_t client]()
> If your sref is not REFERENCE_VREFplus_AVss ||   
> REFERENCE_VREFplus_VREFnegterm
> then you will never call Refvolt_1/2_5V.start()
>
> Now while releasing the resource, imho, we should do the same check
> else we end up with a post switchOff() loop
> as call RefVolt_1_5V.stop() will fail.
>
> async command error_t ClientResource.release[uint8_t client]()
>  {
>      const msp430adc12_channel_config_t* settings  = call  
> Config.getConfiguration[client]();
>      atomic {
>      if (owner == client){                  owner = NO_OWNER;
>          if (settings->sref == REFERENCE_VREFplus_AVss ||
>          settings->sref == REFERENCE_VREFplus_VREFnegterm)
>          post switchOff();
>      }
>      }
>    return call AdcResource.release[client]();
>  }
> seems better or did i miss something?

We discussed this in the core WG meeting today. Jan (who's  
responsible for the MSP430 ADC) is going to take a look. The short  
story is that you've definitely found a bug, but your solution has a  
race condition in it. Our hope is to fix this for the 2.0.1 release;  
Jan will hopefully be getting in touch with you about it.

Phil