linux-kernel - Re: [PATCH] regulator: twl: Enable regulators over the powerbus as well

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Date:	Fri, 25 Mar 2016 15:54:19 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Sebastian Reichel <sre@...nel.org>
Cc:	Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>, tony@...mide.com,
	lgirdwood@...il.com, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: twl: Enable regulators over the powerbus as
 well

On Fri, Mar 25, 2016 at 04:02:59PM +0100, Sebastian Reichel wrote:
> On Fri, Mar 25, 2016 at 11:17:57AM +0000, Mark Brown wrote:
> > On Wed, Mar 23, 2016 at 09:22:36PM +0200, Ivaylo Dimitrov wrote:

> > > Assigning a device group to a regulator does not change its state. To
> > > change the state of a regulator a message over the powerbus is required.
> > > Also, the check for the current state of a regulator should not count on
> > > a device group being assigned, but on the current resource state.

> > How did this driver ever work then?  It sounds like there must be
> > something else going on here.

> From my understanding of the twl4030 TRM assigning a device group
> means "<device group> wants this regulator enabled". It does not
> change the regulator mode (sleep vs normal or in regulator-framework
> terms: REGULATOR_STATUS_NORMAL vs REGULATOR_STATUS_STANDBY).

> It usually works, since the default state is normal. If the system
> is rebooted from a non-mainline kernel, which left the regulator in
> sleep/standby, nothing in the kernel switches it to normal.

I really can't tell how anyone could get from the changelog to what
you're saying about modes.  The explanation needs to be *much* clearer.

Part of the confusion is that if you're trying to do something to do
with the mode support that really needs to use the mode APIs, enabling
or disabling the regulator should not silently change the mode.

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