[PATCH 1/2] ASoC: davinci: Clear VCIF read FIFO on errors

[lexszero@gmail.com (Alexey Ignatov)]

Clearing VCIF read FIFO on overflow and underflow events fixes audio glitching
when DMA load is high. This happened when simultaneously capturing and encoding
video and audio, for example.

Signed-off-by: Alexey Ignatov <lexszero@gmail.com>
---
 sound/soc/davinci/davinci-vcif.c | 60 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 56 insertions(+), 4 deletions(-)

diff --git a/sound/soc/davinci/davinci-vcif.c b/sound/soc/davinci/davinci-vcif.c
index 5bee0427..0d8014e 100644
--- a/sound/soc/davinci/davinci-vcif.c
+++ b/sound/soc/davinci/davinci-vcif.c
@@ -45,6 +45,10 @@
 	} \
 } while (0)
 
+#define DAVINCI_VC_INT_RERR_MASK \
+	(DAVINCI_VC_INT_RERRUDR_MASK | \
+	 DAVINCI_VC_INT_RERROVF_MASK)
+
 struct davinci_vcif_dev {
 	struct davinci_vc *davinci_vc;
 	struct davinci_pcm_dma_params	dma_params[2];
@@ -87,6 +91,22 @@ static void davinci_vcif_stop(struct snd_pcm_substream *substream)
 	writel(w, davinci_vc->base + DAVINCI_VC_CTRL);
 }
 
+static void davinci_vcif_interrupts(struct snd_pcm_substream *substream,
+		int enable)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct davinci_vcif_dev *davinci_vcif_dev =
+			snd_soc_dai_get_drvdata(rtd->cpu_dai);
+	struct davinci_vc *davinci_vc = davinci_vcif_dev->davinci_vc;
+
+	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
+		writel(DAVINCI_VC_INT_RERR_MASK,
+				davinci_vc->base + DAVINCI_VC_INTCLR);
+		writel(enable ? DAVINCI_VC_INT_RERR_MASK : 0,
+				davinci_vc->base + DAVINCI_VC_INTEN);
+	}
+}
+
 static int davinci_vcif_hw_params(struct snd_pcm_substream *substream,
 				  struct snd_pcm_hw_params *params,
 				  struct snd_soc_dai *dai)
@@ -104,10 +124,6 @@ static int davinci_vcif_hw_params(struct snd_pcm_substream *substream,
 	/* General line settings */
 	writel(DAVINCI_VC_CTRL_MASK, davinci_vc->base + DAVINCI_VC_CTRL);
 
-	writel(DAVINCI_VC_INT_MASK, davinci_vc->base + DAVINCI_VC_INTCLR);
-
-	writel(DAVINCI_VC_INT_MASK, davinci_vc->base + DAVINCI_VC_INTEN);
-
 	w = readl(davinci_vc->base + DAVINCI_VC_CTRL);
 
 	/* Determine xfer data type */
@@ -149,6 +165,32 @@ static int davinci_vcif_hw_params(struct snd_pcm_substream *substream,
 	return 0;
 }
 
+static irqreturn_t davinci_vcif_irq_handler(int irq, void *data)
+{
+	struct davinci_vcif_dev *davinci_vcif_dev = data;
+	struct davinci_vc *davinci_vc = davinci_vcif_dev->davinci_vc;
+	uint32_t w;
+
+	w = readl(davinci_vc->base + DAVINCI_VC_INTSTATUS);
+
+	if (w & DAVINCI_VC_INT_RERR_MASK) {
+		pr_debug("vc overflow or underflow occurred, resetting fifo\n");
+
+		w = readl(davinci_vc->base + DAVINCI_VC_CTRL);
+		MOD_REG_BIT(w, DAVINCI_VC_CTRL_RFIFOCL, 1);
+		writel(w, davinci_vc->base + DAVINCI_VC_CTRL);
+
+		w = readl(davinci_vc->base + DAVINCI_VC_CTRL);
+		MOD_REG_BIT(w, DAVINCI_VC_CTRL_RFIFOCL, 0);
+		writel(w, davinci_vc->base + DAVINCI_VC_CTRL);
+
+		writel(DAVINCI_VC_INT_RERR_MASK,
+				davinci_vc->base + DAVINCI_VC_INTCLR);
+	}
+
+	return IRQ_HANDLED;
+}
+
 static int davinci_vcif_trigger(struct snd_pcm_substream *substream, int cmd,
 				struct snd_soc_dai *dai)
 {
@@ -159,10 +201,12 @@ static int davinci_vcif_trigger(struct snd_pcm_substream *substream, int cmd,
 	case SNDRV_PCM_TRIGGER_RESUME:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 		davinci_vcif_start(substream);
+		davinci_vcif_interrupts(substream, 1);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		davinci_vcif_interrupts(substream, 0);
 		davinci_vcif_stop(substream);
 		break;
 	default:
@@ -178,6 +222,7 @@ static int davinci_vcif_startup(struct snd_pcm_substream *substream,
 	struct davinci_vcif_dev *dev = snd_soc_dai_get_drvdata(dai);
 
 	snd_soc_dai_set_dma_data(dai, substream, dev->dma_params);
+
 	return 0;
 }
 
@@ -238,6 +283,13 @@ static int davinci_vcif_probe(struct platform_device *pdev)
 
 	dev_set_drvdata(&pdev->dev, davinci_vcif_dev);
 
+	ret = devm_request_irq(&pdev->dev, IRQ_MBXINT, davinci_vcif_irq_handler,
+			0, "vcif", davinci_vcif_dev);
+	if (ret != 0) {
+		dev_err(&pdev->dev, "could not request irq: %d\n", ret);
+		return ret;
+	}
+
 	ret = snd_soc_register_component(&pdev->dev, &davinci_vcif_component,
 					 &davinci_vcif_dai, 1);
 	if (ret != 0) {
-- 
2.3.5