Re: [RFC 5/8] regulator: anatop: fix min dropout for bypass mode

Leonard Crestez
2017-03-28T11:53:04Z

On Fri, 2017-03-24 at 12:54 +0000, Mark Brown wrote:
> On Wed, Mar 22, 2017 at 06:53:07PM +0200, Leonard Crestez wrote:
> > + if (anatop_reg->bypass)
> > + anatop_reg->rdesc.min_dropout_uV = 0;
> > + else
> > + anatop_reg->rdesc.min_dropout_uV = LDO_MIN_DROPOUT_UV;
> No, this is completely broken - you can't expect to randomly change hthe
> regulator description at runtime behind the back of the framework and
> expect things to work.  If there is a need to do this we need an
> interface for getting the current value and a way to notify of changes.
>
> That said I would not expect the dropout voltage to be considered at
> all when the regulator is bypassed, since the regulator is not
> regulating it doesn't need any headroom.

It's a more complex solution but this could be handled in the core instead.
Basically the core would treat min_dropout_uV as zero if the regulator is
currently in bypass mode.

In theory a function could be added in regulator_ops to ask a regulator driver
what requirements it has for its supply but this does not seem necessary.