ASoC: tas6424: Allow disabling auto diagnostics for faster power-on

The TAS6424 incorporates both DC-load and AC-load diagnostics which are
used to determine the status of the load. The DC diagnostics runs when any
channel is directed to leave the Hi-Z state and enter the MUTE or PLAY
state.
The DC diagnostics are turned on by default but, if a fast startup without
diagnostics is required, the diagnostics can be disabled using a dedicated
ALSA control.
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/tas6424.c

@@ -64,6 +64,8 @@ static const struct snd_kcontrol_new tas6424_snd_controls[] = {
 		       TAS6424_CH3_VOL_CTRL, 0, 0xff, 0, dac_tlv),
 	SOC_SINGLE_TLV("Speaker Driver CH4 Playback Volume",
 		       TAS6424_CH4_VOL_CTRL, 0, 0xff, 0, dac_tlv),
+	SOC_SINGLE_STROBE("Auto Diagnostics Switch", TAS6424_DC_DIAG_CTRL1,
+			  TAS6424_LDGBYPASS_SHIFT, 1),
 };
 
 static int tas6424_dac_event(struct snd_soc_dapm_widget *w,
@@ -297,6 +299,11 @@ static int tas6424_power_on(struct snd_soc_component *component)
 	struct tas6424_data *tas6424 = snd_soc_component_get_drvdata(component);
 	int ret;
 	u8 chan_states;
+	int no_auto_diags = 0;
+	unsigned int reg_val;
+
+	if (!regmap_read(tas6424->regmap, TAS6424_DC_DIAG_CTRL1, &reg_val))
+		no_auto_diags = reg_val & TAS6424_LDGBYPASS_MASK;
 
 	ret = regulator_bulk_enable(ARRAY_SIZE(tas6424->supplies),
 				    tas6424->supplies);
@@ -327,8 +334,10 @@ static int tas6424_power_on(struct snd_soc_component *component)
 	snd_soc_component_write(component, TAS6424_CH_STATE_CTRL, chan_states);
 
 	/* any time we come out of HIZ, the output channels automatically run DC
-	 * load diagnostics, wait here until this completes
+	 * load diagnostics if autodiagnotics are enabled. wait here until this
+	 * completes.
 	 */
+	if (!no_auto_diags)
 		msleep(230);
 
 	return 0;

sound/soc/codecs/tas6424.h

@@ -111,6 +111,10 @@
 					 TAS6424_CH3_STATE_DIAG | \
 					 TAS6424_CH4_STATE_DIAG)
 
+/* TAS6424_DC_DIAG_CTRL1 */
+#define TAS6424_LDGBYPASS_SHIFT		0
+#define TAS6424_LDGBYPASS_MASK		BIT(TAS6424_LDGBYPASS_SHIFT)
+
 /* TAS6424_GLOB_FAULT1_REG */
 #define TAS6424_FAULT_CLOCK		BIT(4)
 #define TAS6424_FAULT_PVDD_OV		BIT(3)