linux-kernel - Re: [PATCH v3 1/2] ASoC: codecs: add TA5720 digital amplifier DT bindings

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Date:	Tue, 26 Apr 2016 17:50:06 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Andreas Dannenberg <dannenberg@...com>
Cc:	alsa-devel@...a-project.org, devicetree@...r.kernel.org,
	Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>,
	Takashi Iwai <tiwai@...e.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] ASoC: codecs: add TA5720 digital amplifier DT
 bindings

On Tue, Apr 26, 2016 at 11:14:25AM -0500, Andreas Dannenberg wrote:
> On Tue, Apr 26, 2016 at 04:37:07PM +0100, Mark Brown wrote:
> > On Mon, Apr 25, 2016 at 03:17:35PM -0500, Andreas Dannenberg wrote:

> > > +Optional properties:

> > > +- dvdd-supply : phandle to a 3.3-V supply for the digital circuitry
> > > +- pvdd-supply : phandle to a supply used for the Class-D amp and the analog

> > This suggests that the device doesn't need power...  

> no power, now that would be nice! :)  What this was supposed to mean is
> that the properties are optional, the power of course is not. The DT has

They should only be optional if they may really be missing.  We may
attempt to be liberal in the DTs we accept but we should not encourage
sloppily written DTs.

> really no control over how I wire up my HW and I'd argue most folks just
> permanently power the TAS5720 since the shutdown current is just a few
> uAs IIRC in order to save some BOM cost. But I suppose the DT description
> is such that the Kernel can more intelligently handle things based on
> what the driver is doing if somebody choses and implements additional
> regulator/power switch HW. Or did I misunderstand your point?

It doesn't really matter if a given system ends up controlling things
actively, we still want to be consistent in describing them since it is
less error prone when it does become relevant.

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