snd_pcm_status() does not update status->avail

[Jaroslav Kysela]

Dne 09. 10. 20 v 16:02 Jonas Holmberg napsal(a):
> Hi,
> I have a problem with status->avail not being updated when using 
> multiple extplug plugins and softvol. I managed to get it to work with 
> the following patch:
> 
> diff --git a/src/pcm/pcm_plugin.c b/src/pcm/pcm_plugin.c
> index ea60eb98..89e819d6 100644
> --- a/src/pcm/pcm_plugin.c
> +++ b/src/pcm/pcm_plugin.c
> @@ -551,6 +551,8 @@ static int snd_pcm_plugin_status(snd_pcm_t *pcm, 
> snd_pcm_status_t * status)
>                  return err;
>          status->appl_ptr = *pcm->appl.ptr;
>          status->hw_ptr = *pcm->hw.ptr;
> +       status->avail = snd_pcm_mmap_capture_avail(pcm);
> +       status->delay = snd_pcm_mmap_capture_delay(pcm);
>          return 0;
>   }
> 
> My question is if this is the correct solution?

It seems that nobody is using those status fields. Usually,
snd_pcm_avail_update() is used by apps. Anyway, this should be fixed for both
directions. The avail should be probably synced to
snd_pcm_plugin_avail_update() output:


diff --git a/src/pcm/pcm_plugin.c b/src/pcm/pcm_plugin.c
index ea60eb98..5739cfc2 100644
--- a/src/pcm/pcm_plugin.c
+++ b/src/pcm/pcm_plugin.c
@@ -541,16 +541,20 @@ static snd_pcm_sframes_t
snd_pcm_plugin_avail_update(snd_pcm_t *pcm)
 static int snd_pcm_plugin_status(snd_pcm_t *pcm, snd_pcm_status_t * status)
 {
        snd_pcm_plugin_t *plugin = pcm->private_data;
-       snd_pcm_sframes_t err;
+       snd_pcm_sframes_t err, avail;

        /* sync with the latest hw and appl ptrs */
-       snd_pcm_plugin_avail_update(pcm);
+       avail = snd_pcm_plugin_avail_update(pcm);
+       if (avail < 0)
+               return avail;

        err = snd_pcm_status(plugin->gen.slave, status);
        if (err < 0)
                return err;
        status->appl_ptr = *pcm->appl.ptr;
        status->hw_ptr = *pcm->hw.ptr;
+       status->avail = avail;
+       status->delay = snd_pcm_mmap_delay(pcm);
        return 0;
 }

					Jaroslav

> 
> BR
> /Jonas
> 


-- 
Jaroslav Kysela <perex at perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.