USB DAC broken since commit bf6313a0ff766925462e97b4e733d5952de02367 (5.10.0-rc5)

[Lennert Van Alboom <lennert@vanalboom.org>]

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Hi,


My USB DAC fails to work on recent kernels (anything past 5.10). The device is the following:

Bus 003 Device 005: ID 2522:0007 LH Labs Geek Out HD Audio 1V5



Syslog shows error messages which have changed over the different kernel versions - this is the output from debian's 5.17.0-2-amd64:

[66136.185642] usb 3-6: uac_clock_source_is_valid(): cannot get clock validity for id 41
[66136.185643] usb 3-6: clock source 41 is not valid, cannot use
[66136.185956] usb 3-6: 1:0: usb_set_interface failed (-71)
[66136.186183] usb 3-6: 1:0: usb_set_interface failed (-71)


From the first point in git where it fails (5.10.0-rc5-00025-gbf6313a0ff76):

Aug 25 12:39:37 Nesbitt kernel: [ 5295.633079] usb 3-3: new high-speed USB device number 8 using xhci_hcd
Aug 25 12:39:37 Nesbitt kernel: [ 5295.782144] usb 3-3: New USB device found, idVendor=2522, idProduct=0007, bcdDevice=15.02
Aug 25 12:39:37 Nesbitt kernel: [ 5295.782148] usb 3-3: New USB device strings: Mfr=1, Product=3, SerialNumber=0
Aug 25 12:39:37 Nesbitt kernel: [ 5295.782150] usb 3-3: Product: Geek Out HD Audio 1V5
Aug 25 12:39:37 Nesbitt kernel: [ 5295.782151] usb 3-3: Manufacturer: LH Labs
Aug 25 12:39:37 Nesbitt kernel: [ 5296.162338] usb 3-3: 1:2 : unsupported format bits 0x100000000
Aug 25 12:39:38 Nesbitt mtp-probe: checking bus 3, device 8: "/sys/devices/pci0000:00/0000:00:14.0/usb3/3-3"
Aug 25 12:39:38 Nesbitt mtp-probe: bus: 3, device: 8 was not an MTP device
Aug 25 12:39:38 Nesbitt systemd-udevd[10311]: controlC1: Process '/usr/sbin/alsactl -E HOME=/run/alsa -E XDG_RUNTIME_DIR=/run/alsa/runtime restore 1' failed with exit code 99.
Aug 25 12:39:38 Nesbitt mtp-probe: checking bus 3, device 8: "/sys/devices/pci0000:00/0000:00:14.0/usb3/3-3"
Aug 25 12:39:38 Nesbitt mtp-probe: bus: 3, device: 8 was not an MTP device
Aug 25 12:39:43 Nesbitt kernel: [ 5301.921810] usb 3-3: 1:1: usb_set_interface failed (-110)
Aug 25 12:39:43 Nesbitt kernel: [ 5301.922047] usb 3-3: 1:0: usb_set_interface failed (-71)
Aug 25 12:39:43 Nesbitt kernel: [ 5301.922354] usb 3-3: 1:0: usb_set_interface failed (-71)
Aug 25 12:39:43 Nesbitt kernel: [ 5301.922915] usb 3-3: 1:0: usb_set_interface failed (-71)


I did a git bisect (from kernel source, not on debian-specific) and the offending commit has been found:

# git bisect bad
bf6313a0ff766925462e97b4e733d5952de02367 is the first bad commit
commit bf6313a0ff766925462e97b4e733d5952de02367
Author: Takashi Iwai <tiwai@suse.de>
Date:   Mon Nov 23 09:53:31 2020 +0100

    ALSA: usb-audio: Refactor endpoint management
    

    This is an intensive surgery for the endpoint and stream management
    for achieving more robust and clean code.
    

    The goals of this patch are:
    - More clear endpoint resource changes
    - The interface altsetting control in a single place
    Below are brief description of the whole changes.
    

    First off, most of the endpoint operations are moved into endpoint.c,
    so that the snd_usb_endpoint object is only referred in other places.
    The endpoint object is acquired and released via the new functions
    snd_usb_endpoint_open() and snd_usb_endpoint_close() that are called
    at PCM hw_params and hw_free callbacks, respectively.  Those are
    ref-counted and EPs can manage the multiple opens.
    

    The open callback receives the audioformat and hw_params arguments,
    and those are used for initializing the EP parameters; especially the
    endpoint, interface and altset numbers are read from there, as well as
    the PCM parameters like the format, rate and channels.  Those are
    stored in snd_usb_endpoint object.  If it's the secondary open, the
    function checks whether the given parameters are compatible with the
    already opened EP setup, too.
    

    The coupling with a sync EP (including an implicit feedback sync) is
    done by the sole snd_usb_endpoint_set_sync() call.
    

    The configuration of each endpoint is done in a single shot via
    snd_usb_endpoint_configure() call.  This is the place where most of
    PCM configurations are done.  A few flags and special handling in the
    snd_usb_substream are dropped along with this change.
    

    A significant difference wrt the configuration from the previous code
    is the order of USB host interface setups.  Now the interface is
    always disabled at beginning and (re-)enabled at the last step of
    snd_usb_endpoint_configure(), in order to be compliant with the
    standard UAC2/3.  For UAC1, the interface is set before the parameter
    setups since there seem devices that require it (e.g. Yamaha THR10),
    just like how it was done in the previous driver code.
    

    The start/stop are almost same as before, also single-shots.  The URB
    callbacks need to be set via snd_usb_endpoint_set_callback() like the
    previous code at the trigger phase, too.
    

    Finally, the flag for the re-setup is set at the device suspend
    through the full EP list, instead of PCM trigger.  This catches the
    overlooked cases where the PCM hasn't been running yet but the device
    needs the full setup after resume.
    

    Tested-by: Keith Milner <kamilner@superlative.org>
    Tested-by: Dylan Robinson <dylan_robinson@motu.com>
    Link: https://lore.kernel.org/r/20201123085347.19667-26-tiwai@suse.de
    Signed-off-by: Takashi Iwai <tiwai@suse.de>

 sound/usb/card.c     |   8 +-
 sound/usb/card.h     |  11 +-
 sound/usb/clock.c    |  13 +-
 sound/usb/endpoint.c | 662 ++++++++++++++++++++++++++-------------------------
 sound/usb/endpoint.h |  40 ++--
 sound/usb/pcm.c      | 616 +++++++++++++++++++----------------------------
 6 files changed, 616 insertions(+), 734 deletions(-)


That's a lot of code though. I'd like to be able to use my DAC on kernels newer than 5.10 so any hints on how to debug and fix this would be greatly appreciated. After doing this 17-point bisect I absolutely don't mind building a few more to fix this.

For info, the debian bug report: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1011196 

For info, a related report from Arch linux for the same device vendor: https://bugs.archlinux.org/task/70636


Thanks,


Lennert

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