On Mon, 17 Aug 2015 18:01:12 +0200, Anssi Hannula wrote: > > Hi, > > 17.08.2015, 17:16, Takashi Iwai kirjoitti: > > On Sun, 16 Aug 2015 14:50:12 +0200, > > Anssi Hannula wrote: > >> > >> 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 causes software using the dB information in > >> e.g. volume sliders to have a massive volume difference in 100..102% > >> range. > >> > >> 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 -53...0 dB. > >> > >> Add a quirk for DragonFly to use a custom dB mapping, based on my > >> measurements, using a 10-item range TLV (so it still fits 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. > >> > >> Signed-off-by: Anssi Hannula <[email protected]> > >> Cc: <[email protected]> > >> --- > >> sound/usb/mixer_quirks.c | 37 +++++++++++++++++++++++++++++++++++++ > >> 1 file changed, 37 insertions(+) > >> > >> diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c > >> index 337c317ead6f..39d7f34e44e6 100644 > >> --- 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" > >> @@ -1733,6 +1734,38 @@ static int snd_microii_controls_create(struct > >> usb_mixer_interface *mixer) > >> return 0; > >> } > >> > >> +static void snd_dragonfly_quirk_db_scale(struct usb_mixer_interface > >> *mixer) > >> +{ > >> + struct usb_mixer_elem_list *list; > >> + struct usb_mixer_elem_info *cval; > >> + static const int unit_id = 7; > >> + > >> + /* approximation using 10 ranges based on output measurement on hw v1.2 > >> */ > >> + 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), > >> + ); > >> + > >> + for (list = mixer->id_elems[unit_id]; list; list = list->next_id_elem) { > >> + cval = (struct usb_mixer_elem_info *)list; > >> + if (cval->control == UAC_FU_VOLUME && > >> + cval->min == 0 && cval->max == 50) { > >> + usb_audio_info(mixer->chip, "applying DragonFly dB > >> scale quirk\n"); > >> + list->kctl->tlv.p = scale; > >> + list->kctl->vd[0].access |= > >> SNDRV_CTL_ELEM_ACCESS_TLV_READ; > >> + list->kctl->vd[0].access &= > >> ~SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK; > >> + } > >> + } > > > > Instead of looking through the list, just hooking at > > build_feature_ctl() would be simpler in the end, I think. > > E.g. something like: > > > > --- a/sound/usb/mixer.c > > +++ b/sound/usb/mixer.c > > @@ -1334,6 +1334,7 @@ static void build_feature_ctl(struct mixer_build > > *state, void *raw_desc, > > SNDRV_CTL_ELEM_ACCESS_TLV_READ | > > SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK; > > } > > + mixer_fu_apply_quirk(state->mixer, cval, unitid, kctl); > > } > > > > range = (cval->max - cval->min) / cval->res; > > > > ... and the quirk implementation in mixer_quirks.c like > > > > static void snd_dragonfly_quirk_db_scale(mixer, kctl) > > { > > 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; > > list->kctl->vd[0].access &= ~SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK; > > } > > > > void mixer_fu_apply_quirk(mixer, cval, unitid, 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; > > } > > } > > OK, seems like a good idea. > > However, I just noticed another volume quirk for DragonFly has already > been merged since I started looking into this: > https://git.kernel.org/cgit/linux/kernel/git/tiwai/sound.git/commit/?id=2d1cb7f658fb9c3ba8f9dab8aca297d4dfdec835 > > It sets a fixed dB linear range map of 0...50dB via mixer_maps.c, which > doesn't seem 100% right to me. While it is much better than the > unquirked 0...0.2dB, it causes e.g. pulseaudio mixer to show the nearly > inaudible raw 0 as the "base" level. And, unless I made some silly > mistake, the volume scale is not actually linear dB AFAICS. > > Yao-Wen, did you have some basis for the assumption "dB conversion > factor is 1" on DragonFly other than that it sounded approximately right? > > Takashi, should I add removal of that "duplicate" quirk in the same > commit (or a separate one)? (assuming my quirk turns out to be actually > better/correct, of course)
Yes, it sounds good. thanks, Takashi -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
