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>

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index f494dced3c11e3a662b93d95df9ea53ff2767dfc..4f85757009b3e44e2246cc21f4387d0948056da3 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1354,6 +1354,8 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
                }
        }
 
+       snd_usb_mixer_fu_apply_quirk(state->mixer, cval, unitid, kctl);
+
        range = (cval->max - cval->min) / cval->res;
        /*
         * Are there devices with volume range more than 255? I use a bit more

diff --git a/sound/usb/mixer_maps.c b/sound/usb/mixer_maps.c
index 6a803eff87f71110049d9c39cb07025d2c64d828..ddca6547399b0103b37abbdf73cfa5c9e710a7fd 100644 (file)
--- a/sound/usb/mixer_maps.c
+++ b/sound/usb/mixer_maps.c
@@ -348,13 +348,6 @@ static struct usbmix_name_map bose_companion5_map[] = {
        { 0 }   /* terminator */
 };
 
-/* Dragonfly DAC 1.2, the dB conversion factor is 1 instead of 256 */
-static struct usbmix_dB_map dragonfly_1_2_dB = {0, 5000};
-static struct usbmix_name_map dragonfly_1_2_map[] = {
-       { 7, NULL, .dB = &dragonfly_1_2_dB },
-       { 0 }   /* terminator */
-};
-
 /*
  * Control map entries
  */
@@ -470,11 +463,6 @@ static struct usbmix_ctl_map usbmix_ctl_maps[] = {
                .id = USB_ID(0x05a7, 0x1020),
                .map = bose_companion5_map,
        },
-       {
-               /* Dragonfly DAC 1.2 */
-               .id = USB_ID(0x21b4, 0x0081),
-               .map = dragonfly_1_2_map,
-       },
        { 0 } /* terminator */
 };
 

diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index fe91184ce83247d8b0360bab09e94c8f7cb720d8..0ce888dceed0ea24db7b677eeb93b05c728ab40a 100644 (file)
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -37,6 +37,7 @@
 #include <sound/control.h>
 #include <sound/hwdep.h>
 #include <sound/info.h>
+#include <sound/tlv.h>
 
 #include "usbaudio.h"
 #include "mixer.h"
@@ -1825,3 +1826,39 @@ void snd_usb_mixer_rc_memory_change(struct usb_mixer_interface *mixer,
        }
 }
 
+static void snd_dragonfly_quirk_db_scale(struct usb_mixer_interface *mixer,
+                                        struct snd_kcontrol *kctl)
+{
+       /* Approximation using 10 ranges based on output measurement on hw v1.2.
+        * This seems close to the cubic mapping e.g. alsamixer uses. */
+       static const DECLARE_TLV_DB_RANGE(scale,
+                0,  1, TLV_DB_MINMAX_ITEM(-5300, -4970),
+                2,  5, TLV_DB_MINMAX_ITEM(-4710, -4160),
+                6,  7, TLV_DB_MINMAX_ITEM(-3884, -3710),
+                8, 14, TLV_DB_MINMAX_ITEM(-3443, -2560),
+               15, 16, TLV_DB_MINMAX_ITEM(-2475, -2324),
+               17, 19, TLV_DB_MINMAX_ITEM(-2228, -2031),
+               20, 26, TLV_DB_MINMAX_ITEM(-1910, -1393),
+               27, 31, TLV_DB_MINMAX_ITEM(-1322, -1032),
+               32, 40, TLV_DB_MINMAX_ITEM(-968, -490),
+               41, 50, TLV_DB_MINMAX_ITEM(-441, 0),
+       );
+
+       usb_audio_info(mixer->chip, "applying DragonFly dB scale quirk\n");
+       kctl->tlv.p = scale;
+       kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
+       kctl->vd[0].access &= ~SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK;
+}
+
+void snd_usb_mixer_fu_apply_quirk(struct usb_mixer_interface *mixer,
+                                 struct usb_mixer_elem_info *cval, int unitid,
+                                 struct snd_kcontrol *kctl)
+{
+       switch (mixer->chip->usb_id) {
+       case USB_ID(0x21b4, 0x0081): /* AudioQuest DragonFly */
+               if (unitid == 7 && cval->min == 0 && cval->max == 50)
+                       snd_dragonfly_quirk_db_scale(mixer, kctl);
+               break;
+       }
+}
+

diff --git a/sound/usb/mixer_quirks.h b/sound/usb/mixer_quirks.h
index bdbfab093816a59772353635fd38eae79ddb3b38..177c329cd4ddb792e144f4ecd945976e6ab9b1a4 100644 (file)
--- 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 */