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authorAnssi Hannula <anssi.hannula@iki.fi>2015-12-13 21:49:58 +0300
committerTakashi Iwai <tiwai@suse.de>2015-12-14 12:13:17 +0300
commit42e3121d90f42e57f6dbd6083dff2f57b3ec7daa (patch)
tree57c53b919f92c3a88a2f815dd630a5eb18c40eb3 /sound/usb/mixer_quirks.h
parent9f9499ae8e6415cefc4fe0a96ad0e27864353c89 (diff)
downloadlinux-42e3121d90f42e57f6dbd6083dff2f57b3ec7daa.tar.xz
ALSA: usb-audio: Add a more accurate volume quirk for AudioQuest DragonFly
AudioQuest DragonFly DAC reports a volume control range of 0..50 (0x0000..0x0032) which in USB Audio means a range of 0 .. 0.2dB, which is obviously incorrect and would cause software using the dB information in e.g. volume sliders to have a massive volume difference in 100..102% range. Commit 2d1cb7f658fb ("ALSA: usb-audio: add dB range mapping for some devices") added a dB range mapping for it with range 0..50 dB. However, the actual volume mapping seems to be neither linear volume nor linear dB scale, but instead quite close to the cubic mapping e.g. alsamixer uses, with a range of approx. -53...0 dB. Replace the previous quirk with a custom dB mapping based on some basic output measurements, using a 10-item range TLV (which will still fit in alsa-lib MAX_TLV_RANGE_SIZE). Tested on AudioQuest DragonFly HW v1.2. The quirk is only applied if the range is 0..50, so if this gets fixed/changed in later HW revisions it will no longer be applied. v2: incorporated Takashi Iwai's suggestion for the quirk application method Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/usb/mixer_quirks.h')
-rw-r--r--sound/usb/mixer_quirks.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/sound/usb/mixer_quirks.h b/sound/usb/mixer_quirks.h
index bdbfab093816..177c329cd4dd 100644
--- a/sound/usb/mixer_quirks.h
+++ b/sound/usb/mixer_quirks.h
@@ -9,5 +9,9 @@ void snd_emuusb_set_samplerate(struct snd_usb_audio *chip,
void snd_usb_mixer_rc_memory_change(struct usb_mixer_interface *mixer,
int unitid);
+void snd_usb_mixer_fu_apply_quirk(struct usb_mixer_interface *mixer,
+ struct usb_mixer_elem_info *cval, int unitid,
+ struct snd_kcontrol *kctl);
+
#endif /* SND_USB_MIXER_QUIRKS_H */