Re: [PATCH] ASoC: fsl_esai: Add spin lock to protect reset and stop

[S.j. Wang]

Hi
> 
> On Wed, Oct 23, 2019 at 03:29:49PM +0800, Shengjiu Wang wrote:
> > xrun may happen at the end of stream, the
> > trigger->fsl_esai_trigger_stop maybe called in the middle of
> > fsl_esai_hw_reset, this may cause esai in wrong state after stop, and
> > there may be endless xrun interrupt.
> 
> What about fsl_esai_trigger_start? It touches ESAI_xFCR_xFEN bit that is
> being checked in the beginning of fsl_esai_hw_reset.
> 
> Could the scenario below be possible also?
> 
> 1) ESAI TX starts
> 2) Xrun happens to TX
> 3) Starting fsl_esai_hw_reset (enabled[TX] = true; enabled[RX] = false)
> 4) ESAI RX starts
> 5) Finishing fsl_esai_hw_reset (enabled[RX] is still false)
> 
> 
Good catch, this may possible.  Will update in v2.

Best regards
Wang shengjiu

Re: [PATCH] ASoC: fsl_esai: Add spin lock to protect reset and stop

[Nicolin Chen]

On Wed, Oct 23, 2019 at 03:29:49PM +0800, Shengjiu Wang wrote:
> xrun may happen at the end of stream, the
> trigger->fsl_esai_trigger_stop maybe called in the middle of
> fsl_esai_hw_reset, this may cause esai in wrong state
> after stop, and there may be endless xrun interrupt.

What about fsl_esai_trigger_start? It touches ESAI_xFCR_xFEN bit
that is being checked in the beginning of fsl_esai_hw_reset.

Could the scenario below be possible also?

1) ESAI TX starts
2) Xrun happens to TX
3) Starting fsl_esai_hw_reset (enabled[TX] = true; enabled[RX] = false)
4) ESAI RX starts
5) Finishing fsl_esai_hw_reset (enabled[RX] is still false)

Thanks
Nicolin

> So Add spin lock to lock these two function.
> 
> Fixes: 7ccafa2b3879 ("ASoC: fsl_esai: recover the channel swap after xrun")
> Signed-off-by: Shengjiu Wang 
> ---
>  sound/soc/fsl/fsl_esai.c | 10 ++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/sound/soc/fsl/fsl_esai.c b/sound/soc/fsl/fsl_esai.c
> index 37b14c48b537..6a797648b66d 100644
> --- a/sound/soc/fsl/fsl_esai.c
> +++ b/sound/soc/fsl/fsl_esai.c
> @@ -33,6 +33,7 @@
>   * @fsysclk: system clock source to derive HCK, SCK and FS
>   * @spbaclk: SPBA clock (optional, depending on SoC design)
>   * @task: tasklet to handle the reset operation
> + * @lock: spin lock to handle reset and stop behavior
>   * @fifo_depth: depth of tx/rx FIFO
>   * @slot_width: width of each DAI slot
>   * @slots: number of slots
> @@ -56,6 +57,7 @@ struct fsl_esai {
>   struct clk *fsysclk;
>   struct clk *spbaclk;
>   struct tasklet_struct task;
> + spinlock_t lock; /* Protect reset and stop */
>   u32 fifo_depth;
>   u32 slot_width;
>   u32 slots;
> @@ -676,8 +678,10 @@ static void fsl_esai_hw_reset(unsigned long arg)
>  {
>   struct fsl_esai *esai_priv = (struct fsl_esai *)arg;
>   bool tx = true, rx = false, enabled[2];
> + unsigned long lock_flags;
>   u32 tfcr, rfcr;
>  
> + spin_lock_irqsave(_priv->lock, lock_flags);
>   /* Save the registers */
>   regmap_read(esai_priv->regmap, REG_ESAI_TFCR, );
>   regmap_read(esai_priv->regmap, REG_ESAI_RFCR, );
> @@ -715,6 +719,8 @@ static void fsl_esai_hw_reset(unsigned long arg)
>   fsl_esai_trigger_start(esai_priv, tx);
>   if (enabled[rx])
>   fsl_esai_trigger_start(esai_priv, rx);
> +
> + spin_unlock_irqrestore(_priv->lock, lock_flags);
>  }
>  
>  static int fsl_esai_trigger(struct snd_pcm_substream *substream, int cmd,
> @@ -722,6 +728,7 @@ static int fsl_esai_trigger(struct snd_pcm_substream 
> *substream, int cmd,
>  {
>   struct fsl_esai *esai_priv = snd_soc_dai_get_drvdata(dai);
>   bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
> + unsigned long lock_flags;
>  
>   esai_priv->channels[tx] = substream->runtime->channels;
>  
> @@ -734,7 +741,9 @@ static int fsl_esai_trigger(struct snd_pcm_substream 
> *substream, int cmd,
>   case SNDRV_PCM_TRIGGER_SUSPEND:
>   case SNDRV_PCM_TRIGGER_STOP:
>   case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
> + spin_lock_irqsave(_priv->lock, lock_flags);
>   fsl_esai_trigger_stop(esai_priv, tx);
> + spin_unlock_irqrestore(_priv->lock, lock_flags);
>   break;
>   default:
>   return -EINVAL;
> @@ -1002,6 +1011,7 @@ static int fsl_esai_probe(struct platform_device *pdev)
>  
>   dev_set_drvdata(>dev, esai_priv);
>  
> + spin_lock_init(_priv->lock);
>   ret = fsl_esai_hw_init(esai_priv);
>   if (ret)
>   return ret;
> -- 
> 2.21.0
> 

[PATCH] ASoC: fsl_esai: Add spin lock to protect reset and stop

[Shengjiu Wang]

xrun may happen at the end of stream, the
trigger->fsl_esai_trigger_stop maybe called in the middle of
fsl_esai_hw_reset, this may cause esai in wrong state
after stop, and there may be endless xrun interrupt.
So Add spin lock to lock these two function.

Fixes: 7ccafa2b3879 ("ASoC: fsl_esai: recover the channel swap after xrun")
Signed-off-by: Shengjiu Wang 
---
 sound/soc/fsl/fsl_esai.c | 10 ++
 1 file changed, 10 insertions(+)

diff --git a/sound/soc/fsl/fsl_esai.c b/sound/soc/fsl/fsl_esai.c
index 37b14c48b537..6a797648b66d 100644
--- a/sound/soc/fsl/fsl_esai.c
+++ b/sound/soc/fsl/fsl_esai.c
@@ -33,6 +33,7 @@
  * @fsysclk: system clock source to derive HCK, SCK and FS
  * @spbaclk: SPBA clock (optional, depending on SoC design)
  * @task: tasklet to handle the reset operation
+ * @lock: spin lock to handle reset and stop behavior
  * @fifo_depth: depth of tx/rx FIFO
  * @slot_width: width of each DAI slot
  * @slots: number of slots
@@ -56,6 +57,7 @@ struct fsl_esai {
struct clk *fsysclk;
struct clk *spbaclk;
struct tasklet_struct task;
+   spinlock_t lock; /* Protect reset and stop */
u32 fifo_depth;
u32 slot_width;
u32 slots;
@@ -676,8 +678,10 @@ static void fsl_esai_hw_reset(unsigned long arg)
 {
struct fsl_esai *esai_priv = (struct fsl_esai *)arg;
bool tx = true, rx = false, enabled[2];
+   unsigned long lock_flags;
u32 tfcr, rfcr;
 
+   spin_lock_irqsave(_priv->lock, lock_flags);
/* Save the registers */
regmap_read(esai_priv->regmap, REG_ESAI_TFCR, );
regmap_read(esai_priv->regmap, REG_ESAI_RFCR, );
@@ -715,6 +719,8 @@ static void fsl_esai_hw_reset(unsigned long arg)
fsl_esai_trigger_start(esai_priv, tx);
if (enabled[rx])
fsl_esai_trigger_start(esai_priv, rx);
+
+   spin_unlock_irqrestore(_priv->lock, lock_flags);
 }
 
 static int fsl_esai_trigger(struct snd_pcm_substream *substream, int cmd,
@@ -722,6 +728,7 @@ static int fsl_esai_trigger(struct snd_pcm_substream 
*substream, int cmd,
 {
struct fsl_esai *esai_priv = snd_soc_dai_get_drvdata(dai);
bool tx = substream->stream == SNDRV_PCM_STREAM_PLAYBACK;
+   unsigned long lock_flags;
 
esai_priv->channels[tx] = substream->runtime->channels;
 
@@ -734,7 +741,9 @@ static int fsl_esai_trigger(struct snd_pcm_substream 
*substream, int cmd,
case SNDRV_PCM_TRIGGER_SUSPEND:
case SNDRV_PCM_TRIGGER_STOP:
case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+   spin_lock_irqsave(_priv->lock, lock_flags);
fsl_esai_trigger_stop(esai_priv, tx);
+   spin_unlock_irqrestore(_priv->lock, lock_flags);
break;
default:
return -EINVAL;
@@ -1002,6 +1011,7 @@ static int fsl_esai_probe(struct platform_device *pdev)
 
dev_set_drvdata(>dev, esai_priv);
 
+   spin_lock_init(_priv->lock);
ret = fsl_esai_hw_init(esai_priv);
if (ret)
return ret;
-- 
2.21.0