linux-kernel - Re: [RFC PATCH 0/5] Apple Macs machine-level ASoC driver

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Date:   Fri, 22 Apr 2022 14:06:37 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Martin Povišer <povik@...ebit.org>
Cc:     Martin Povišer <povik+lin@...ebit.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Mark Kettenis <kettenis@...nbsd.org>,
        Hector Martin <marcan@...can.st>,
        Sven Peter <sven@...npeter.dev>
Subject: Re: [RFC PATCH 0/5] Apple Macs machine-level ASoC driver

On Fri, Apr 22, 2022 at 02:53:54PM +0200, Martin Povišer wrote:

> > Oh, I see - the speaker actually allows configuration of the slots
> > independently.  Usually the left/right thing on mono devices only does
> > something for I2S where the bus clocking enforces that there be both
> > left and right channels.  Either configuration is fine by me TBH, if you
> > can do that then you could just keep them mapped to the same channel
> > then mark the control as disabled since it should have no effect.

> Well but is there some established way to mark a control as disabled?

snd_ctl_activate_id().

> Another issue here is that if I disable it I can’t leave the routing
> control in it’s default value, which is ‘I2C Offset’ and makes the speaker
> amp ignore the slot mapping.

Sure, that's fine - if a control genuinely has no effect it's fine to
hide it from userspace.  The issue is where it's just that you don't see
the use, if the control demonstrably does nothing then that's fine.

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