2010/6/17 Takashi Iwai tiwai@suse.de
At Thu, 17 Jun 2010 08:35:54 +0800, Raymond Yau wrote:
http://git.alsa-project.org/?p=alsa-utils.git;a=commit;h=c9b86f49a8a1a8c337b...
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;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
But the application can use snd_mixer_selem_set_playback_volume_range() to set min and max of the control ,
is there any reason allow the application to set this range ?
it seem that snd_mixer_selem_set_playback_volume did not performe any range check
correct me if I am wrong, I seem able to use snd_mixer_selem_set_playback_volume to -1 for the pulse device and there is no error return , but I get another value when use snd_mixer_selem_get_playback_volume
BTW, amixer has -nocheck option to bypass the range check but this option seem unable to set the value of "Master playback volume" toabove max