[alsa-devel] [PATCH] ASoC: soc-pcm: do not hw_free BE if it's still used

[Liam Girdwood]

On Wed, 2014-12-03 at 10:13 +0800, Qiao Zhou wrote:
> Do not free BE hw if it's still used by other FE during dpcm runtime
> shutdown. Otherwise the BE runtime state will be STATE_HW_FREE and
> won't be updated to STATE_CLOSE when shutdown ends, because BE dai
> shutdown function won't close pcm when detecting BE is still under
> use. With STATE_HW_FREE, BE can't be triggered start again.
> 
> This corner case can easily appear when one BE is used by two FE,
> without this patch "ASoC: dpcm: Fix race between FE/BE updates and
> trigger"(ea9d0d771fcd32cd56070819749477d511ec9117). One FE tries to
> shutdown but it's raced against xrun on another FE. It improves the
> be dai hw_free logic.
> 
> Signed-off-by: Qiao Zhou <zhouqiao at marvell.com>

Acked-by: Liam Girdwood <liam.r.girdwood at linux.intel.com>

> ---
>  sound/soc/soc-pcm.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
> index 57277dd..70e8088 100644
> --- a/sound/soc/soc-pcm.c
> +++ b/sound/soc/soc-pcm.c
> @@ -1664,6 +1664,10 @@ int dpcm_be_dai_hw_free(struct snd_soc_pcm_runtime *fe, int stream)
>  		if (!snd_soc_dpcm_can_be_free_stop(fe, be, stream))
>  				continue;
>  
> +		/* do not free hw if this BE is used by other FE */
> +		if (be->dpcm[stream].users > 1)
> +			continue;
> +
>  		if ((be->dpcm[stream].state != SND_SOC_DPCM_STATE_HW_PARAMS) &&
>  		    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_PREPARE) &&
>  		    (be->dpcm[stream].state != SND_SOC_DPCM_STATE_HW_FREE) &&