ASoC: codecs: msm8916-wcd-analog: use btn0 released detection

msm8916-wcd-analog uses button0 to differentiate between headphone and
headset. Under some circumstances, button pressed and released
interrupts are not fired as the driver expects it.

For instance, with some connectors, there are spurious button-pressed
interrupts when unplugging a headphone, without the corresponding
button-released interrupt. But the codec always alternates between
button pressed and released interrupts, it cannot fire two interrupts of
the same kind in a row. That means that when the headphone is plugged
back, only a button-released interrupt will be fired instead of pressed
then released. This causes the driver to report headphone as headset.

By changing the logic and relying on button 0 release interrupt, the
driver could be made more robust for connectors that differ from the one
used on the Dragonboard's audio mezzanine.
Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/msm8916-wcd-analog.c

@@ -285,7 +285,7 @@ struct pm8916_wcd_analog_priv {
 	u16 codec_version;
 	bool	mbhc_btn_enabled;
 	/* special event to detect accessory type */
-	bool	mbhc_btn0_pressed;
+	int	mbhc_btn0_released;
 	bool	detect_accessory_type;
 	struct clk *mclk;
 	struct snd_soc_codec *codec;
@@ -483,7 +483,7 @@ static void pm8916_wcd_setup_mbhc(struct pm8916_wcd_analog_priv *wcd)
 
 	snd_soc_update_bits(codec, CDC_D_INT_EN_CLR, int_en_mask, 0);
 	snd_soc_update_bits(codec, CDC_D_INT_EN_SET, int_en_mask, int_en_mask);
-	wcd->mbhc_btn0_pressed = false;
+	wcd->mbhc_btn0_released = false;
 	wcd->detect_accessory_type = true;
 }
 
@@ -950,7 +950,7 @@ static irqreturn_t mbhc_btn_release_irq_handler(int irq, void *arg)
 
 		/* check if its BTN0 thats released */
 		if ((val != -1) && !(val & CDC_A_MBHC_RESULT_1_BTN_RESULT_MASK))
-			priv->mbhc_btn0_pressed = false;
+			priv->mbhc_btn0_released = true;
 
 	} else {
 		snd_soc_jack_report(priv->jack, 0, btn_mask);
@@ -983,9 +983,7 @@ static irqreturn_t mbhc_btn_press_irq_handler(int irq, void *arg)
 		break;
 	case 0x0:
 		/* handle BTN_0 specially for type detection */
-		if (priv->detect_accessory_type)
-			priv->mbhc_btn0_pressed = true;
-		else
+		if (!priv->detect_accessory_type)
 			snd_soc_jack_report(priv->jack,
 					    SND_JACK_BTN_0, btn_mask);
 		break;
@@ -1029,19 +1027,19 @@ static irqreturn_t pm8916_mbhc_switch_irq_handler(int irq, void *arg)
 		 * both press and release event received then its
 		 * a headset.
 		 */
-		if (priv->mbhc_btn0_pressed)
+		if (priv->mbhc_btn0_released)
 			snd_soc_jack_report(priv->jack,
-					    SND_JACK_HEADPHONE, hs_jack_mask);
+					    SND_JACK_HEADSET, hs_jack_mask);
 		else
 			snd_soc_jack_report(priv->jack,
-					    SND_JACK_HEADSET, hs_jack_mask);
+					    SND_JACK_HEADPHONE, hs_jack_mask);
 
 		priv->detect_accessory_type = false;
 
 	} else { /* removal */
 		snd_soc_jack_report(priv->jack, 0, hs_jack_mask);
 		priv->detect_accessory_type = true;
-		priv->mbhc_btn0_pressed = false;
+		priv->mbhc_btn0_released = false;
 	}
 
 	return IRQ_HANDLED;