ASoC: dapm: Initialise kcontrol data for mux/demux controls

DAPM keeps a copy of the current value of mux/demux controls,
however this value is only initialised in the case of autodisable
controls. This leads to false notification events when first
modifying a DAPM kcontrol that has a non-zero default.

Autodisable controls are left as they are, since they already
initialise the value, and there would be more work required to
support autodisable muxes where the first option isn't disabled
and/or that isn't the default.

Technically this issue could affect mixer/switch elements as well,
although not on any of the devices I am currently running. There
is also a little more work to do to address the issue there due to
that side supporting stereo controls, so that has not been tackled
in this patch.
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20220623105120.1981154-1-ckeepax@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-dapm.c

@@ -62,6 +62,8 @@ struct snd_soc_dapm_widget *
 snd_soc_dapm_new_control_unlocked(struct snd_soc_dapm_context *dapm,
 			 const struct snd_soc_dapm_widget *widget);
 
+static unsigned int soc_dapm_read(struct snd_soc_dapm_context *dapm, int reg);
+
 /* dapm power sequences - make this per codec in the future */
 static int dapm_up_seq[] = {
 	[snd_soc_dapm_pre] = 1,
@@ -442,6 +444,9 @@ static int dapm_kcontrol_data_alloc(struct snd_soc_dapm_widget *widget,
 
 			snd_soc_dapm_add_path(widget->dapm, data->widget,
 					      widget, NULL, NULL);
+		} else if (e->reg != SND_SOC_NOPM) {
+			data->value = soc_dapm_read(widget->dapm, e->reg) &
+				      (e->mask << e->shift_l);
 		}
 		break;
 	default: