[PATCH] [SOUND] recording gain control

Viral Mehta
2009-03-10T05:30:27Z

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);

Thanks,
Viral

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