ASoC: Warn if WM8903 platform data is used to enable microphone IRQ

The WM8903 interrupts are clear on read so if the WM8903 detection is
enabled from platform data when the IRQ is in use (rather than using a
direct signal from a GPIO) status may be lost during startup. Help users
spot this misconfiguration by adding a WARN_ON().

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>

sound/soc/codecs/wm8903.c

@@ -1917,12 +1917,26 @@ static int wm8903_probe(struct snd_soc_codec *codec)
 
 	/* Set up GPIOs and microphone detection */
 	if (pdata) {
+		bool mic_gpio = false;
+
 		for (i = 0; i < ARRAY_SIZE(pdata->gpio_cfg); i++) {
 			if (pdata->gpio_cfg[i] == WM8903_GPIO_NO_CONFIG)
 				continue;
 
 			snd_soc_write(codec, WM8903_GPIO_CONTROL_1 + i,
 				      pdata->gpio_cfg[i] & 0xffff);
+
+			val = (pdata->gpio_cfg[i] & WM8903_GP1_FN_MASK)
+				>> WM8903_GP1_FN_SHIFT;
+
+			switch (val) {
+			case WM8903_GPn_FN_MICBIAS_CURRENT_DETECT:
+			case WM8903_GPn_FN_MICBIAS_SHORT_DETECT:
+				mic_gpio = true;
+				break;
+			default:
+				break;
+			}
 		}
 
 		snd_soc_write(codec, WM8903_MIC_BIAS_CONTROL_0,
@@ -1933,6 +1947,14 @@ static int wm8903_probe(struct snd_soc_codec *codec)
 			snd_soc_update_bits(codec, WM8903_WRITE_SEQUENCER_0,
 					    WM8903_WSEQ_ENA, WM8903_WSEQ_ENA);
 
+		/* If microphone detection is enabled by pdata but
+		 * detected via IRQ then interrupts can be lost before
+		 * the machine driver has set up microphone detection
+		 * IRQs as the IRQs are clear on read.  The detection
+		 * will be enabled when the machine driver configures.
+		 */
+		WARN_ON(!mic_gpio && (pdata->micdet_cfg & WM8903_MICDET_ENA));
+
 		wm8903->mic_delay = pdata->micdet_delay;
 	}