[PATCH] ASoC: es9356: fix the capture gain dB scale

[PATCH] ASoC: es9356: fix the capture gain dB scale

[Zachary Huang]

The two capture gain controls are declared with a TLV step of 3 (FU33,
analog mic) and 6 (FU11, DMIC).  The TLV step is expressed in 0.01 dB
units, so this advertises 0.03 dB and 0.06 dB per step: with a value
range of 0..10 and 0..3 the whole controls appear to span only 0.30 dB
and 0.18 dB.

The hardware steps are 3 dB and 6 dB, i.e. 0..30 dB and 0..18 dB.
Measured on a MECHREVO WUJIE 14SAH (ES9356 on SoundWire link 0) by
recording the same signal at all four FU11 settings:

    FU11=0   rms  523  (-35.9 dBFS)
    FU11=1   rms 1007  (-30.3 dBFS)
    FU11=2   rms 2011  (-24.2 dBFS)
    FU11=3   rms 3794  (-18.7 dBFS)

That is about +6 dB per step, matching the hardware definition rather
than the advertised 0.06 dB.

Because userspace (alsamixer, PipeWire/WirePlumber) derives the volume
from this TLV, the capture gain currently looks like a control without
any usable range, which is also why the default setting seems impossible
to raise from the desktop.

Assisted-by: LLM
Signed-off-by: Zachary Huang <zuzhenhuang365@gmail.com>
---
 sound/soc/codecs/es9356.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/soc/codecs/es9356.c b/sound/soc/codecs/es9356.c
index c54bf05..ce48b1e 100644
--- a/sound/soc/codecs/es9356.c
+++ b/sound/soc/codecs/es9356.c
@@ -74,8 +74,8 @@ static int es9356_sdw_component_probe(struct snd_soc_component *component)
 }
 
 static const DECLARE_TLV_DB_SCALE(out_vol_tlv, -9600, 12, 0);
-static const DECLARE_TLV_DB_SCALE(amic_gain_tlv, 0, 3, 0);
-static const DECLARE_TLV_DB_SCALE(dmic_gain_tlv, 0, 6, 0);
+static const DECLARE_TLV_DB_SCALE(amic_gain_tlv, 0, 300, 0);
+static const DECLARE_TLV_DB_SCALE(dmic_gain_tlv, 0, 600, 0);
 
 static const struct snd_kcontrol_new es9356_sdca_controls[] = {
 	SDCA_SINGLE_Q78_TLV("FU41 Left Playback Volume",
-- 
2.53.0

Re: [PATCH] ASoC: es9356: fix the capture gain dB scale

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] ASoC: es9356: missing Fixes trailer for commit 5d9cb740cd38
--

commit 52267100487603f3acb6a660175cdbfe55292773
Author: Zachary Huang <zuzhenhuang365@gmail.com>

> ASoC: es9356: fix the capture gain dB scale
>
> The two capture gain controls are declared with a TLV step of 3 (FU33,
> analog mic) and 6 (FU11, DMIC).  The TLV step is expressed in 0.01 dB
> units, so this advertises 0.03 dB and 0.06 dB per step: with a value
> range of 0..10 and 0..3 the whole controls appear to span only 0.30 dB
> and 0.18 dB.
>
> The hardware steps are 3 dB and 6 dB, i.e. 0..30 dB and 0..18 dB.
> Measured on a MECHREVO WUJIE 14SAH (ES9356 on SoundWire link 0) by
> recording the same signal at all four FU11 settings:
>
>     FU11=0   rms  523  (-35.9 dBFS)
>     FU11=1   rms 1007  (-30.3 dBFS)
>     FU11=2   rms 2011  (-24.2 dBFS)
>     FU11=3   rms 3794  (-18.7 dBFS)
>
> That is about +6 dB per step, matching the hardware definition rather
> than the advertised 0.06 dB.
>
> Because userspace (alsamixer, PipeWire/WirePlumber) derives the volume
> from this TLV, the capture gain currently looks like a control without
> any usable range, which is also why the default setting seems impossible
> to raise from the desktop.
>
> Assisted-by: LLM
> Signed-off-by: Zachary Huang <zuzhenhuang365@gmail.com>

[Severity: Low]
Should this bug fix include a Fixes: tag for the commit that introduced
the driver with the wrong TLV step units:

  Fixes: 5d9cb740cd38 ("ASoC: es9356-sdca: Add ES9356 SDCA driver")

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/179398005797.39773.18432202435074682955@gmail.com?part=1