Re: [alsa-devel] [PATCH v6 02/11] mfd: wcd934x: add support to wcd9340/wcd9341 codec

[Pierre-Louis Bossart]

> > > Note these are the child devices of the MFD SLIMBus device.
> >
> > Ah ok. I guess the creation of those child devices when the parent 
> > SLIMbus device reports PRESENT initially if fine, it's the part where 
> > you remove them if the device loses sync or gets powered off which is 
> > odd. And I guess technically you could still have race conditions 
> > where a child device starts a transaction just as the parent is no 
> > longer attached to the bus.
>
> Losing power to SLIMBus device is very odd usecase and if it happens 
> suggests that threre are bigger issues on the board design itself. This 
> case should never happen. Even if it happens we would get timeout errors 
> on every SLIMbus transactions.
>
> > > > I would however not remove the devices when the status is down but 
> > > > only on an explicit .remove.
> > >
> > > Am open for suggestions but I would not like the child devices to 
> > > talk on the bus once the SLIMbus device is down! Only way to ensure 
> > > or make it silent is to remove.
> >
> > it's as if you are missing a mechanism to forward the parent status to 
> > the children so use remove() for lack of a better solution?
> That is true. This gives bit more control on the slave device lifecycle.
> Current solution works fine for now with less complexities across 
> multiple drivers. I also agree that there is scope of improvement in 
> future for this.

ok, makes sense, thanks for the answers. No further questions, so

Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>