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[ALSA] Add TLV support to snd-usb-audio driver

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Added TLV-read support to snd-usb-audio driver for passing
the volume dB scale information to user-space.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>
This commit is contained in:
Takashi Iwai 2006-07-14 15:18:19 +02:00 committed by Jaroslav Kysela
parent 6a65d793b0
commit 7bc5ba7e02
1 changed files with 27 additions and 0 deletions
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27
sound/usb/usbmixer.c
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@ -37,6 +37,7 @@
#include <sound/control.h>
#include <sound/hwdep.h>
#include <sound/info.h>
#include <sound/tlv.h>
#include "usbaudio.h"
@ -416,6 +417,26 @@ static inline int set_cur_mix_value(struct usb_mixer_elem_info *cval, int channe
return set_ctl_value(cval, SET_CUR, (cval->control << 8) | channel, value);
}
/*
* TLV callback for mixer volume controls
*/
static int mixer_vol_tlv(struct snd_kcontrol *kcontrol, int op_flag,
unsigned int size, unsigned int __user *_tlv)
{
struct usb_mixer_elem_info *cval = kcontrol->private_data;
DECLARE_TLV_DB_SCALE(scale, 0, 0, 0);
if (size < sizeof(scale))
return -ENOMEM;
/* USB descriptions contain the dB scale in 1/256 dB unit
* while ALSA TLV contains in 1/100 dB unit
*/
scale[2] = (convert_signed_value(cval, cval->min) * 100) / 256;
scale[3] = (convert_signed_value(cval, cval->res) * 100) / 256;
if (copy_to_user(_tlv, scale, sizeof(scale)))
return -EFAULT;
return 0;
}
/*
* parser routines begin here...
@ -933,6 +954,12 @@ static void build_feature_ctl(struct mixer_build *state, unsigned char *desc,
}
strlcat(kctl->id.name + len, control == USB_FEATURE_MUTE ? " Switch" : " Volume",
sizeof(kctl->id.name));
if (control == USB_FEATURE_VOLUME) {
kctl->tlv.c = mixer_vol_tlv;
kctl->vd[0].access |=
SNDRV_CTL_ELEM_ACCESS_TLV_READ |
SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
}
break;
default: