linux-kernel - Re: [PATCH] ASoC: codecs: wcd938x: fix dB range for HPHL and HPHR

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Message-ID: <56aecc8d-2f6c-42c0-a13a-89c84cf53773@sirena.org.uk>
Date:   Fri, 7 Jul 2023 16:06:24 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Johan Hovold <johan@...nel.org>, perex@...ex.cz,
        tiwai@...e.com, lgirdwood@...il.com, ckeepax@...nsource.cirrus.com,
        kuninori.morimoto.gx@...esas.com, linux-kernel@...r.kernel.org,
        pierre-louis.bossart@...ux.intel.com, alsa-devel@...a-project.org
Subject: Re: [PATCH] ASoC: codecs: wcd938x: fix dB range for HPHL and HPHR

On Fri, Jul 07, 2023 at 03:47:47PM +0200, Takashi Iwai wrote:
> Mark Brown wrote:

> > The ASoC generic control stuff supports inverting the value prior to
> > presentation to userspace so it's masked there (instead of writing the
> > number userspace sees to the register we subtract the number from the
> > maximum value and write that to the register), pulling that up further
> > to the ALSA core might be nice I guess?

> I believe yes.  Though, I'm still not sure how we can improve the
> mismatch of dB min/max.  The dB values of those inverted controls
> reflect the result of subtraction, no?

Yes, the dB scale presented to userspace is reversed relative to the
ordering in the registers.

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