linux-kernel - Re: [PATCH 1/3] ASoC: es8316: Increment max value for ALC Capture Target Volume control

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Date:   Fri, 26 May 2023 21:11:49 +0300
From:   Cristian Ciocaltea <cristian.ciocaltea@...labora.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Zhu Ning <zhuning0077@...il.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        David Yang <yangxiaohua@...rest-semi.com>,
        Daniel Drake <drake@...lessm.com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        alsa-devel@...a-project.org, kernel@...labora.com
Subject: Re: [PATCH 1/3] ASoC: es8316: Increment max value for ALC Capture
 Target Volume control

On 5/24/23 16:59, Mark Brown wrote:
> On Wed, May 24, 2023 at 04:49:37PM +0300, Cristian Ciocaltea wrote:
>> On 5/24/23 13:30, Mark Brown wrote:
> 
>>> Presumably you can check the effects of changing the value?  It seems
>>> plausible that what's written in the code might be accurate and the
>>> higher values might actually change the gain but it'd be better to
>>> check.
> 
>> I haven't noticed a (measurable) change in gain when switching between
>> 10 and 11, but my testing equipment is also not that great. Will try to
>> improve the tests accuracy.
> 
> I'd expect it should be really obvious with a scope if you've got one?
> Testing with something consistent like a sine wave (eg, from
> speaker-test) should also make a 1.5dB difference noticable enough to
> check if there's at least a volume change by ear even if you can't
> specifically quantify it.

Luckily arecord & aplay provide VU meter support (via -V,
--vumeter=TYPE'), so I could easily verify this without using any
additional tools:

 Volume  |  VU meter
---------+----------
-6.0 dB  |  30-31 %
-4.5 dB  |  35-36 %
-3.0 dB  |  42-43 %
-1.5 dB  |  50-51 %
-0.0 dB  |  50-51 %

So it seems the specs are correct, and the problem is the hardware default.

Is there a better approach to handle this than extending the volume range?

Regards,
Cristian