ASoC: tlv320aic32x4: Fix problem with first capture.

In its previous status, the first capture didn't work properly;
nothing was actually recorded from the microphone. This
behaviour was observed using a Visstrim M10 board.

In order to solve this BUG a workaround has been added that,
during the initialization process of the codec, powers on and
off the ADC.

The issue seems related to a HW BUG or some behavior that
is not documented in the datasheet.
Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/tlv320aic32x4.c

@@ -675,6 +675,16 @@ static int aic32x4_probe(struct snd_soc_codec *codec)
 			     ARRAY_SIZE(aic32x4_snd_controls));
 	aic32x4_add_widgets(codec);
 
+	/*
+	 * Workaround: for an unknown reason, the ADC needs to be powered up
+	 * and down for the first capture to work properly. It seems related to
+	 * a HW BUG or some kind of behavior not documented in the datasheet.
+	 */
+	tmp_reg = snd_soc_read(codec, AIC32X4_ADCSETUP);
+	snd_soc_write(codec, AIC32X4_ADCSETUP, tmp_reg |
+				AIC32X4_LADC_EN | AIC32X4_RADC_EN);
+	snd_soc_write(codec, AIC32X4_ADCSETUP, tmp_reg);
+
 	return 0;
 }
 

sound/soc/codecs/tlv320aic32x4.h

@@ -94,6 +94,9 @@
 #define AIC32X4_WORD_LEN_24BITS		0x02
 #define AIC32X4_WORD_LEN_32BITS		0x03
 
+#define AIC32X4_LADC_EN			(1 << 7)
+#define AIC32X4_RADC_EN			(1 << 6)
+
 #define AIC32X4_I2S_MODE		0x00
 #define AIC32X4_DSP_MODE		0x01
 #define AIC32X4_RIGHT_JUSTIFIED_MODE	0x02