ASoC: stm32: i2s: fix IRQ clearing

Because of regmap cache, interrupts may not be cleared
as expected.
Declare IFCR register as write only and make writings
to IFCR register unconditional.
Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/stm/stm32_i2s.c

@@ -247,8 +247,8 @@ static irqreturn_t stm32_i2s_isr(int irq, void *devid)
 		return IRQ_NONE;
 	}
 
-	regmap_update_bits(i2s->regmap, STM32_I2S_IFCR_REG,
-			   I2S_IFCR_MASK, flags);
+	regmap_write_bits(i2s->regmap, STM32_I2S_IFCR_REG,
+			  I2S_IFCR_MASK, flags);
 
 	if (flags & I2S_SR_OVR) {
 		dev_dbg(&pdev->dev, "Overrun\n");
@@ -277,7 +277,6 @@ static bool stm32_i2s_readable_reg(struct device *dev, unsigned int reg)
 	case STM32_I2S_CFG2_REG:
 	case STM32_I2S_IER_REG:
 	case STM32_I2S_SR_REG:
-	case STM32_I2S_IFCR_REG:
 	case STM32_I2S_TXDR_REG:
 	case STM32_I2S_RXDR_REG:
 	case STM32_I2S_CGFR_REG:
@@ -559,8 +558,8 @@ static int stm32_i2s_startup(struct snd_pcm_substream *substream,
 	i2s->refcount++;
 	spin_unlock(&i2s->lock_fd);
 
-	return regmap_update_bits(i2s->regmap, STM32_I2S_IFCR_REG,
-				  I2S_IFCR_MASK, I2S_IFCR_MASK);
+	return regmap_write_bits(i2s->regmap, STM32_I2S_IFCR_REG,
+				 I2S_IFCR_MASK, I2S_IFCR_MASK);
 }
 
 static int stm32_i2s_hw_params(struct snd_pcm_substream *substream,
@@ -611,8 +610,8 @@ static int stm32_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
 			return ret;
 		}
 
-		regmap_update_bits(i2s->regmap, STM32_I2S_IFCR_REG,
-				   I2S_IFCR_MASK, I2S_IFCR_MASK);
+		regmap_write_bits(i2s->regmap, STM32_I2S_IFCR_REG,
+				  I2S_IFCR_MASK, I2S_IFCR_MASK);
 
 		if (playback_flg) {
 			ier = I2S_IER_UDRIE;