Re: [PATCH] at73c213: Fix DMA size at the end of DMA buffer

[Takashi Iwai <tiwai@suse.de>]

At Mon, 17 Mar 2008 22:00:27 +0900 (JST),
Atsushi Nemoto wrote:
> 
> On Fri, 14 Mar 2008 14:39:42 +0100, Takashi Iwai <tiwai@suse.de> wrote:
> > Add the following constraint in the open callback:
> > 
> > 	err = snd_pcm_hw_constraint_integer(runtime,
> > 					SNDRV_PCM_HW_PARAM_PERIODS);
> > 	if (err < 0)
> > 		return err;
> > 
> > This will guarantee that the period size fits with the buffer size.
> 
> Thank you!  It works fine.  Here is a new patch.

Thanks for the patch.  So, I should revert your last patch, right?
It's already on ALSA tree...


Takashi

> 
> ------------------------------------------------------
> Subject: [PATCH] at73c213: Add constraints for periods value
> From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
> 
> The interrupt handler always provide runtime->period_size data, so it
> works correctly only if buffer_size was a multiple of period_size.
> 
> This patch fixes periodic click noise.
> 
> Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
> ---
> This patch obsoletes a patch titled "at73c213: fix DMA size at the end
> of DMA buffer" in git-alsa-tiwai.patch in mm tree.
> 
> diff --git a/sound/spi/at73c213.c b/sound/spi/at73c213.c
> index 7c077c6..9a5c118 100644
> --- a/sound/spi/at73c213.c
> +++ b/sound/spi/at73c213.c
> @@ -210,7 +210,13 @@ static int snd_at73c213_pcm_open(struct snd_pcm_substream *substream)
>  {
>  	struct snd_at73c213 *chip = snd_pcm_substream_chip(substream);
>  	struct snd_pcm_runtime *runtime = substream->runtime;
> +	int err;
>  
> +	/* ensure buffer_size is a multiple of period_size */
> +	err = snd_pcm_hw_constraint_integer(runtime,
> +					SNDRV_PCM_HW_PARAM_PERIODS);
> +	if (err < 0)
> +		return err;
>  	snd_at73c213_playback_hw.rate_min = chip->bitrate;
>  	snd_at73c213_playback_hw.rate_max = chip->bitrate;
>  	runtime->hw = snd_at73c213_playback_hw;
>