[alsa-devel] [ALSA patch] [PATCH 2/5] pcm: dshare: Added "hw_ptr_alignment" option in configuration for alignment of slave pointers

[Takashi Iwai]

On Tue, 30 Apr 2019 09:38:40 +0200,
<vanitha.channaiah at in.bosch.com> wrote:
> 
> From: Vanitha Channaiah <vanitha.channaiah at in.bosch.com>
> 
> snd_pcm_wait() is waiting for longer time more than two periodic size as
> avail is less than avail_min by few frames.
> This is because the hw_ptr read from the kernel during snd_pcm_start()
> is not period aligned which is ahead of few frames.
> 
> These changes are adaptation of same fix as given for dmix
> commit ("6b058fda9dce8f416774ae54975f5706f3f5a6da")
> ("pcm-dmix-Add-option-to-allow-alignment-of-slave-poin.patch")
> 
> Signed-off-by: Vanitha Channaiah <vanitha.channaiah at in.bosch.com>

Again, this patch description is too ambiguous.

And, if it enables the hw_ptr_alignment option, update the
documentation as well.


thanks,

Takashi

> ---
>  src/pcm/pcm_dshare.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/src/pcm/pcm_dshare.c b/src/pcm/pcm_dshare.c
> index f135b5d..45e2597 100644
> --- a/src/pcm/pcm_dshare.c
> +++ b/src/pcm/pcm_dshare.c
> @@ -333,16 +333,16 @@ static int snd_pcm_dshare_reset(snd_pcm_t *pcm)
>  	snd_pcm_direct_t *dshare = pcm->private_data;
>  	dshare->hw_ptr %= pcm->period_size;
>  	dshare->appl_ptr = dshare->last_appl_ptr = dshare->hw_ptr;
> -	dshare->slave_appl_ptr = dshare->slave_hw_ptr = *dshare->spcm->hw.ptr;
> +	snd_pcm_direct_reset_slave_ptr(pcm, dshare);
>  	return 0;
>  }
>  
> -static int snd_pcm_dshare_start_timer(snd_pcm_direct_t *dshare)
> +static int snd_pcm_dshare_start_timer(snd_pcm_t *pcm, snd_pcm_direct_t *dshare)
>  {
>  	int err;
>  
>  	snd_pcm_hwsync(dshare->spcm);
> -	dshare->slave_appl_ptr = dshare->slave_hw_ptr = *dshare->spcm->hw.ptr;
> +	snd_pcm_direct_reset_slave_ptr(pcm, dshare);
>  	err = snd_timer_start(dshare->timer);
>  	if (err < 0)
>  		return err;
> @@ -364,7 +364,8 @@ static int snd_pcm_dshare_start(snd_pcm_t *pcm)
>  	else if (avail < 0)
>  		return 0;
>  	else {
> -		if ((err = snd_pcm_dshare_start_timer(dshare)) < 0)
> +		err = snd_pcm_dshare_start_timer(pcm, dshare);
> +		if (err < 0)
>  			return err;
>  		snd_pcm_dshare_sync_area(pcm);
>  	}
> @@ -547,7 +548,8 @@ static snd_pcm_sframes_t snd_pcm_dshare_mmap_commit(snd_pcm_t *pcm,
>  		return 0;
>  	snd_pcm_mmap_appl_forward(pcm, size);
>  	if (dshare->state == STATE_RUN_PENDING) {
> -		if ((err = snd_pcm_dshare_start_timer(dshare)) < 0)
> +		err = snd_pcm_dshare_start_timer(pcm, dshare);
> +		if (err < 0)
>  			return err;
>  	} else if (dshare->state == SND_PCM_STATE_RUNNING ||
>  		   dshare->state == SND_PCM_STATE_DRAINING) {
> @@ -755,6 +757,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
>  	dshare->slowptr = opts->slowptr;
>  	dshare->max_periods = opts->max_periods;
>  	dshare->var_periodsize = opts->var_periodsize;
> +	dshare->hw_ptr_alignment = opts->hw_ptr_alignment;
>  	dshare->sync_ptr = snd_pcm_dshare_sync_ptr;
>  
>   retry:
> -- 
> 2.7.4
> 
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