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[ALSA] Add TLV support to snd-usb-audio driver
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>
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@ -37,6 +37,7 @@
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#include <sound/control.h>
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#include <sound/hwdep.h>
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#include <sound/info.h>
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#include <sound/tlv.h>
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#include "usbaudio.h"
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@ -416,6 +417,26 @@ static inline int set_cur_mix_value(struct usb_mixer_elem_info *cval, int channe
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return set_ctl_value(cval, SET_CUR, (cval->control << 8) | channel, value);
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}
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/*
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* TLV callback for mixer volume controls
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*/
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static int mixer_vol_tlv(struct snd_kcontrol *kcontrol, int op_flag,
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unsigned int size, unsigned int __user *_tlv)
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{
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struct usb_mixer_elem_info *cval = kcontrol->private_data;
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DECLARE_TLV_DB_SCALE(scale, 0, 0, 0);
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if (size < sizeof(scale))
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return -ENOMEM;
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/* USB descriptions contain the dB scale in 1/256 dB unit
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* while ALSA TLV contains in 1/100 dB unit
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*/
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scale[2] = (convert_signed_value(cval, cval->min) * 100) / 256;
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scale[3] = (convert_signed_value(cval, cval->res) * 100) / 256;
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if (copy_to_user(_tlv, scale, sizeof(scale)))
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return -EFAULT;
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return 0;
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}
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/*
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* parser routines begin here...
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@ -933,6 +954,12 @@ static void build_feature_ctl(struct mixer_build *state, unsigned char *desc,
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}
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strlcat(kctl->id.name + len, control == USB_FEATURE_MUTE ? " Switch" : " Volume",
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sizeof(kctl->id.name));
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if (control == USB_FEATURE_VOLUME) {
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kctl->tlv.c = mixer_vol_tlv;
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kctl->vd[0].access |=
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SNDRV_CTL_ELEM_ACCESS_TLV_READ |
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SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
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}
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break;
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default:
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