ASoC: tas2770: Power cycle amp on ISENSE/VSENSE change

The ISENSE/VSENSE blocks are only powered up when the amplifier
transitions from shutdown to active. This means that if those controls
are flipped on while the amplifier is already playing back audio, they
will have no effect.

Fix this by forcing a power cycle around transitions in those controls.

Reviewed-by: Neal Gompa <[e-mail]>
Signed-off-by: Hector Martin <[e-mail]>
Signed-off-by: James Calligeros <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/codecs/tas2770.c

···
 static const struct snd_kcontrol_new vsense_switch =
 	SOC_DAPM_SINGLE("Switch", TAS2770_PWR_CTRL, 2, 1, 1);
 
+static int sense_event(struct snd_soc_dapm_widget *w,
+			struct snd_kcontrol *kcontrol, int event)
+{
+	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
+	struct tas2770_priv *tas2770 = snd_soc_component_get_drvdata(component);
+
+	/*
+	 * Powering up ISENSE/VSENSE requires a trip through the shutdown state.
+	 * Do that here to ensure that our changes are applied properly, otherwise
+	 * we might end up with non-functional IVSENSE if playback started earlier,
+	 * which would break software speaker protection.
+	 */
+	switch (event) {
+	case SND_SOC_DAPM_PRE_REG:
+		return snd_soc_component_update_bits(component, TAS2770_PWR_CTRL,
+						    TAS2770_PWR_CTRL_MASK,
+						    TAS2770_PWR_CTRL_SHUTDOWN);
+	case SND_SOC_DAPM_POST_REG:
+		return tas2770_update_pwr_ctrl(tas2770);
+	default:
+		return 0;
+	}
+}
+
 static const struct snd_soc_dapm_widget tas2770_dapm_widgets[] = {
 	SND_SOC_DAPM_AIF_IN("ASI1", "ASI1 Playback", 0, SND_SOC_NOPM, 0, 0),
 	SND_SOC_DAPM_MUX("ASI1 Sel", SND_SOC_NOPM, 0, 0, &tas2770_asi1_mux),
-	SND_SOC_DAPM_SWITCH("ISENSE", TAS2770_PWR_CTRL, 3, 1, &isense_switch),
-	SND_SOC_DAPM_SWITCH("VSENSE", TAS2770_PWR_CTRL, 2, 1, &vsense_switch),
+	SND_SOC_DAPM_SWITCH_E("ISENSE", TAS2770_PWR_CTRL, 3, 1, &isense_switch,
+		sense_event, SND_SOC_DAPM_PRE_REG | SND_SOC_DAPM_POST_REG),
+	SND_SOC_DAPM_SWITCH_E("VSENSE", TAS2770_PWR_CTRL, 2, 1, &vsense_switch,
+		sense_event, SND_SOC_DAPM_PRE_REG | SND_SOC_DAPM_POST_REG),
 	SND_SOC_DAPM_DAC_E("DAC", NULL, SND_SOC_NOPM, 0, 0, tas2770_dac_event,
 			   SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_PRE_PMD),
 	SND_SOC_DAPM_OUTPUT("OUT"),