Re: [alsa-devel] [PATCH] [SOUND] recording gain control

Takashi Iwai
2009-03-10T12:59:31Z

At Tue, 10 Mar 2009 17:52:46 +0530,
Viral Mehta wrote:
>
> Takashi Iwai wrote:
> > At Tue, 10 Mar 2009 10:00:13 +0100,
> > Clemens Ladisch wrote:
> >
> >> (CC alsa-devel)
> >>
> >> Viral Mehta wrote:
> >>
> >>> Hi,
> >>>
> >>> I am trying to do gain control while RECORDING for my Audio Mic device.
> >>>
> >>> My application opens /dev/mixer device and calls ioctl(fdmixer,
> >>> MIXER_WRITE(SOUND_MIXER_MIC), ...)
> >>>
> >>> But, the call fails. It traces to sound/core/oss/mixer_oss.c file and
> >>> snd_mixer_oss_put_volume1() function.
> >>> It never falls in "if (slot->present & SNDRV_MIXER_OSS_PRESENT_CVOLUME)"
> >>> as condition "if (slot->present & SNDRV_MIXER_OSS_PRESENT_PVOLUME) "
> >>> comes as false.
> >>>
> >>> I think there is a bug in kernel and I think it should be like as below,
> >>>
> >>> --- sound/core/oss/mixer_oss.c 2008-12-03 13:24:02.000000000 +0530
> >>> +++ sound/core/oss/mixer_oss.c 2009-03-09 16:22:06.548766896 +0530
> >>> @@ -688,7 +688,7 @@ static int snd_mixer_oss_put_volume1(str
> >>>
> >>> if (slot->present & SNDRV_MIXER_OSS_PRESENT_PVOLUME) {
> >>> snd_mixer_oss_put_volume1_vol(fmixer, pslot,
> >>> slot->numid[SNDRV_MIXER_OSS_ITEM_PVOLUME], left, right);
> >>> - if (slot->present & SNDRV_MIXER_OSS_PRESENT_CVOLUME)
> >>> + } else if (slot->present & SNDRV_MIXER_OSS_PRESENT_CVOLUME) {
> >>> snd_mixer_oss_put_volume1_vol(fmixer, pslot,
> >>> slot->numid[SNDRV_MIXER_OSS_ITEM_CVOLUME], left, right);
> >>> } else if (slot->present & SNDRV_MIXER_OSS_PRESENT_GVOLUME) {
> >>> snd_mixer_oss_put_volume1_vol(fmixer, pslot,
> >>> slot->numid[SNDRV_MIXER_OSS_ITEM_GVOLUME], left, right);
> >>>
> >> Your mailer mangled the patch; see linux/Documentation/email-clients.txt.
> >>
> >
> > Also, the current code behaves intentionally so (as it's designed for
> > mic-loopback volume).
> >
> > A more feasible fix would be to add another if check for *_CVOLUME
> > instead of moving it.
> >
> >
> >
> Oh okie. It makes sense.
> I just sent out a patch on LAD. Should I resubmit with what you proposed ?

LAD is no good place for sending a patch of sound driver.
Please post to alsa-devel ML (and add Cc to me).

thanks,

Takashi