linux-kernel - Re: [PATCH 1/2] ASoC: davinci: Clear VCIF read FIFO on errors

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Date:	Fri, 10 Apr 2015 10:19:28 +0300
From:	Peter Ujfalusi <peter.ujfalusi@...com>
To:	Alexey Ignatov <lexszero@...il.com>,
	<davinci-linux-open-source@...ux.davincidsp.com>
CC:	Sekhar Nori <nsekhar@...com>,
	Kevin Hilman <khilman@...prootsystems.com>,
	Wolfram Sang <wsa@...-dreams.de>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <alsa-devel@...a-project.org>
Subject: Re: [PATCH 1/2] ASoC: davinci: Clear VCIF read FIFO on errors

On 04/10/2015 02:00 AM, Alexey Ignatov wrote:
> 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@...il.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;
> +	}

I would make this optional to avoid regression if the arch patch is not present.

> +
>  	ret = snd_soc_register_component(&pdev->dev, &davinci_vcif_component,
>  					 &davinci_vcif_dai, 1);
>  	if (ret != 0) {
> 


-- 
Péter
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