linux-kernel - Re: Question about regulator API

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Message-ID: <20161216165348.mha6d3faucxdript@sirena.org.uk>
Date:   Fri, 16 Dec 2016 16:53:48 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Harald Geyer <harald@...ib.org>
Cc:     Liam Girdwood <lgirdwood@...il.com>, linux-kernel@...r.kernel.org
Subject: Re: Question about regulator API

On Fri, Dec 16, 2016 at 02:41:42PM +0100, Harald Geyer wrote:
> Mark Brown writes:
> > On Wed, Dec 14, 2016 at 03:52:54PM +0100, Harald Geyer wrote:

> > This doesn't feel like a regulator API problem exactly, a lot of what
> > you're talking about here seems like you really need the devices to
> > coopereate with each other and know what they're doing in order to work
> > well together.

> I was hoping, that I somehow could get the necessary coordination from
> the regulator framework. If the best I can get ATM is notifications, then
> I'll try it and see what kind of code falls out of this.

> It still seems a bit of a limitation to me, that the only way to really
> switch off a regulator is with regulator_force_disable(), which is quite
> a hard hammer.

I really have no idea what sort of communication you're envisaging here
- powering supplies down when other devices are trying to use them is a
really serious thing with very substantial consequences for userspace,
if the devices aren't cooperating at a level higher than the regulator
API level it's unlikely to go well.

> This only works as long as every consumer of the supply is cooperating
> (which is my personal use case but doesn't look very future proof). I guess
> there has to be some pain for using quirky, unreliable HW... ;)

That's going to be the case no matter what I think.

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