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


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