[Sound-open-firmware] [PATCH] component: don't report xrun in comp_copy().

[Liam Girdwood]

On Tue, 2018-01-16 at 22:05 +0800, Keyon Jie wrote:
> We don't need to report xrun every time it can't do real
> copy(buffer avail/free not enough),

Why ? what problem is this solving ?

>  e.g. we actually don't
> need copy if sink buffer is full, we should do empty copy
> and return success to let pipeline schedule continue.
> 
> The xrun will be checked in scheduling component (usually
> is dai) only and reported there.
> 
> Todo: remove xrun check in other components also, e.g.
> mixer, src, etc.
> 
> Signed-off-by: Keyon Jie <yang.jie at linux.intel.com>
> ---
> Sanity test passed on minnow turbot with rt5651.
> SOF #master: commit 83fec1559716d5a06137b43848abc18c244bc9e6
> SOF Tool #master: commit a6bb8de907acd642302a227f403bb9fb2c18d075
> Kernel: git at github.com:plbossart/sound.git #topic/sof-v4.14:
>         commit 772ab0da7a8298d08edd42ab9a4f4177ec37aec6
> 
>  src/audio/host.c   |  6 +++---
>  src/audio/volume.c | 12 ++++++------
>  2 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/src/audio/host.c b/src/audio/host.c
> index 7cba6df..0a047b3 100644
> --- a/src/audio/host.c
> +++ b/src/audio/host.c
> @@ -622,9 +622,9 @@ static int host_copy(struct comp_dev *dev)
>  
>  		if (dma_buffer->free < local_elem->size) {
>  			/* make sure there is free bytes for next period */
> -			trace_host_error("xro");
> -			comp_overrun(dev, dma_buffer, local_elem->size, 0);
> -			return -EIO;
> +			/* dont be too nervous, just warning and return */
> +			trace_host("xo?");

How will host userspace know about XRUN ?

Also this means that the xrun will propagate through the pipeline (as
each sink/source may underrun or overrun until xrun clears) causing a
longer overall audio artefact.

Liam

> +			return 0;
>  		}
>  	} else {
>  
> diff --git a/src/audio/volume.c b/src/audio/volume.c
> index 05459b8..9ea3c92 100644
> --- a/src/audio/volume.c
> +++ b/src/audio/volume.c
> @@ -577,14 +577,14 @@ static int volume_copy(struct comp_dev *dev)
>  	 * the sink component buffer has enough free bytes for copy. Also
>  	 * check for XRUNs */
>  	if (source->avail < cd->source_period_bytes) {
> -		trace_volume_error("xru");
> -		comp_underrun(dev, source, cd->source_period_bytes, 0);
> -		return -EIO;	/* xrun */
> +		/* dont be too nervous, just warning if can't copy this time */
> +		trace_volume("xu?");
> +		return 0; /* don't break the pipeline */
>  	}
>  	if (sink->free < cd->sink_period_bytes) {
> -		trace_volume_error("xro");
> -		comp_overrun(dev, sink, cd->sink_period_bytes, 0);
> -		return -EIO;	/* xrun */
> +		/* dont be too nervous, just warning if can't copy this time */
> +		trace_volume_error("xo?");
> +		return 0; /* don't break the pipeline */
>  	}
>  
>  	/* copy and scale volume */