ASoC: intel/sdw_utils: Add volume limit to cs42l43 speakers

The volume control for cs42l43 speakers has a maximum gain of +31.5 dB.
However, for many use cases, this can cause distorted audio, depending
various factors, such as other signal-processing elements in the chain,
for example if the audio passes through a gain control before reaching
the codec or the signal path has been tuned for a particular maximum
gain in the codec.

In the case of systems which use the soc_sdw_cs42l43 driver, audio will
likely be distorted in all cases above 0 dB, therefore add a volume
limit of 128, which is 0 dB maximum volume inside this driver.

Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250430103134.24579-2-sbinding@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/sdw_utils/soc_sdw_cs42l43.c b/sound/soc/sdw_utils/soc_sdw_cs42l43.c
index 668c9d2..b415d45 100644 (file)
--- a/sound/soc/sdw_utils/soc_sdw_cs42l43.c
+++ b/sound/soc/sdw_utils/soc_sdw_cs42l43.c
@@ -20,6 +20,8 @@
 #include <sound/soc-dapm.h>
 #include <sound/soc_sdw_utils.h>
 
+#define CS42L43_SPK_VOLUME_0DB 128 /* 0dB Max */
+
 static const struct snd_soc_dapm_route cs42l43_hs_map[] = {
        { "Headphone", NULL, "cs42l43 AMP3_OUT" },
        { "Headphone", NULL, "cs42l43 AMP4_OUT" },
@@ -117,6 +119,14 @@ int asoc_sdw_cs42l43_spk_rtd_init(struct snd_soc_pcm_runtime *rtd, struct snd_so
                        return -ENOMEM;
        }
 
+       ret = snd_soc_limit_volume(card, "cs42l43 Speaker Digital Volume",
+                                  CS42L43_SPK_VOLUME_0DB);
+       if (ret)
+               dev_err(card->dev, "cs42l43 speaker volume limit failed: %d\n", ret);
+       else
+               dev_info(card->dev, "Setting CS42L43 Speaker volume limit to %d\n",
+                        CS42L43_SPK_VOLUME_0DB);
+
        ret = snd_soc_dapm_add_routes(&card->dapm, cs42l43_spk_map,
                                      ARRAY_SIZE(cs42l43_spk_map));
        if (ret)