[alsa-devel] [PATCH] Two patches for Alsa-plugins (pulse)

Takashi Iwai tiwai at suse.de
Thu Jun 24 08:42:19 CEST 2010

At Wed, 23 Jun 2010 21:57:01 +0200,
David Henningsson wrote:
> These two patches are being used in Ubuntu Lucid (released this April)
> and are working well enough to have people asking us to backport them to
> Karmic. Today I got an email, asking for the upstream status of one of
> these patches, since he wanted them in Fedora. If posting them here
> isn't the correct way to upstream them, please tell me so.
> The first one (Fix invalid buffer pointer return value) fixes broken logic:
> This patch improves recovering from underruns, and prevents hangs inside
> snd_pcm_write* and snd_pcm_read* due to snd_pcm_avail* returning too
> low values. It especially helps low latency situations.

This one looks OK.  Applied now.

> The second one (Do not report underruns to the ALSA layer) is more a
> change of behavior, which could be questioned. The arguments for
> removing that code are these:
>  * If pulseaudio gets an underrun, the normal way to end that underrun
> is to feed it with more buffers. This is different from the ALSA way of
> dealing with underruns, which requires hardware buffer pointers to be reset.
>  * In addition, underrun signals are delivered asynchronously from
> pulseaudio. This means that there might be more buffers on the way to
> pulseaudio when the underrun is reported, making the underrun obsolete.
> Unfortunately, there is currently no known way to determine whether this
> is the case or not.

I think this helps for normal use-cases, so it'd be good to apply.
But, I prefer having a runtime option for such a behavior change
(although the default value can be the new behavior).

Care to add it?



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