linux-kernel - Re: [PATCH] ASoC: pcm: allow changing the playback/capture rates for symmetric links

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Message-ID: <20160504164922.GB6292@sirena.org.uk>
Date:	Wed, 4 May 2016 17:49:22 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Peter Rosin <peda@...ntia.se>
Cc:	alsa-devel@...a-project.org, Liam Girdwood <lgirdwood@...il.com>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: pcm: allow changing the playback/capture rates for
 symmetric links

On Mon, May 02, 2016 at 09:43:53AM +0200, Peter Rosin wrote:

> The problem is in the drain/close part. If I leave out snd_pcm_drain
> I naturally lose the tail of the output, but if I have it I get what
> I guess is a repeat of the content in some circular buffer. I.e. the
> very last part of the played sound is played twice(ice).

> If I instead write the generated samples to a file and play them
> with aplay, all is fine, so I appear to be misunderstanding the
> alsa api?

> Anything obviously wrong in the above code?

Look at how aplay handles this...  it's a natural consequence of the
hardware being free running.  You need to either make the teardown
non-blocking or play some silence at the end.

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