[alsa-devel] snd_mixer_selem_get_playback_volume return value outside allowed range

[Takashi Iwai]

At Thu, 17 Jun 2010 08:35:54 +0800,
Raymond Yau wrote:
> 
> 2010/5/25 Clemens Ladisch <clemens at ladisch.de>
> 
> > James Courtier-Dutton wrote:
> > > On 25 May 2010 09:38, Clemens Ladisch <clemens at ladisch.de> wrote:
> > > > All the others seem to be mistakes:
> > > >
> > > > > soc/codecs/stac9766.c:...
> > > > > soc/codecs/wm8350.c:...
> > > > > soc/codecs/wm8400.c:...
> > > > > soc/codecs/wm8990.c:...
> > >
> > > Could this maybe explain why pulseaudio was having such problems with
> > > alsa with regards to gain controls????
> >
> > Only if it happens on embedded hardware that uses these particular
> > codecs.
> >
> >
> > Regards,
> > Clemens
> >
> 
> http://git.alsa-project.org/?p=alsa-utils.git;a=commit;h=c9b86f49a8a1a8c337bf0c1b7f12749e8be781ed
> 
> your patch did not fix the buggy driver (e.g. alsa-pulse plugin) which
> return volume outside the alllowed range
> 
> 
> amixer -D pulse
> Simple mixer control 'Master',0
>   Capabilities: pvolume pswitch pswitch-joined
>   Playback channels: Front Left - Front Right
>   Limits: Playback 0 - 65536
>   Mono:
>   Front Left: Playback 98304 [150%] [on]
>   Front Right: Playback 98304 [150%] [on]
> 
> 
> 
> 
> Should snd_mixer_selem_get_playback_volume() perform range check ?
> 
> tatic int get_volume_ops(snd_mixer_elem_t *elem, int dir,
>               snd_mixer_selem_channel_id_t channel, long *value)
> {
>     selem_none_t *s = snd_mixer_elem_get_private(elem);
>     if (s->selem.caps & SM_CAP_GVOLUME)
>         dir = SM_PLAY;
>     if ((unsigned int) channel >= s->str[dir].channels)
>         return -EINVAL;
>     *value = s->str[dir].vol[channel];
> +       if (*value > s->str[dir].max)
> +                return -EINVAL;
> +       if (*value < s->str[dir].min)
> +                return -EINVAL;
>     return 0;

Some sanity check would be nice, but returning -EINVAL here isn't
correct, at least.  -EINVAL should be returned when the caller gives a
wrong value (e.g. a wrong channel value).


Takashi