[Alsa-user] snd-usb-audio - USB DAC can't set sample frequency

[Michal Š. <ms...@gm...>]

Hello to all,

yesterday i had a chance to try new Zodiac Platinum DAC
(http://www.antelopeaudio.com/en/products/Zodiac-Platinum-DSD-DAC-DA-Converter)
at my friend's studio. I was really excited to check it out with Linux
and MPD, because it supports DoP (DSD over PCM), which i never tried
before. Unfortunately, i was unsuccessful with it. Every attempt to
playback (both PCM or DoP) failed with unsuccessful setting of right
sample rate at hardware (Fs is indicated on its faceplate).

alsa-info output with some details is there:
http://www.alsa-project.org/db/?f=9a37130d95a5acc5ec019ab08509367ebe7c7ccb

DAC itself has two switchable USB HiSpeed modes: UH1, which is UAC1
according to dump (bInterfaceProtocol is 0) with maximum sample rate
192k (this itself surprised me as i always thought, UAC1 is associated
with 24/96 limit). And UH2, which is UAC2 and supports rates up to
384k. I tried both, but none was working.
Kernel messages are like this: "ALSA clock.c:309 7:1:1: cannot get
freq at ep 0x5", when in UAC1 and "ALSA clock.c:391 current rate 44100
is different from the runtime rate 96000", when in UAC2.
Corresponding link to source:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/sound/usb/clock.c?id=v3.10
USB dumps for both modes are attached. For comparison i've
successfully tested their lower model DAC (Zodiac Gold) in UH1 mode up
to 192k and also attached USB dump.
Just for completeness of information, Zodiac Platinum is working
properly (and just to say that, it sounds absolutely amazing) with
Windows and their Thesycon based USB audio driver, so particular
hardware isn't faulty. And i also tried newer kernel 3.12.5-301 from
rawhide with same result.

Can you spot some obvious thing, when comparing dumps and values at
descriptors? I'll have another chance to test it more thoroughly and
we will definitely write ticket to manufacturers support. But i would
like to find out more about error we encountered, so i will be very
happy for any comment or tip, what is possible to try at Linux side.

Thank you,

Michal