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Commit 59bb7f0e authored by Takashi Iwai's avatar Takashi Iwai
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ALSA: usb-audio - Don't expose broken dB ranges 



Some crappy USB-audio devices give broken dB ranges, e.g. both min and max
are 0dB.  This confuses the volume control that prefers dB expression such
as alsactl or PulseAudio.  In such a case, it's much better not to expose
the broken dB information.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 13eb4ab8

sound/usb/mixer.c

+6 −4
Original line number Diff line number Diff line
@@ -1097,11 +1097,13 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc, 
		append_ctl_name(kctl, control == UAC_FU_MUTE ?

				" Switch" : " Volume");

		if (control == UAC_FU_VOLUME) {

			check_mapped_dB(map, cval);

			if (cval->dBmin < cval->dBmax) {

				kctl->tlv.c = mixer_vol_tlv;

				kctl->vd[0].access |= 

					SNDRV_CTL_ELEM_ACCESS_TLV_READ |

					SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;

			check_mapped_dB(map, cval);

			}

		}

		break;