• Takashi Iwai's avatar
    ALSA: usb-audio: Fix regression on Sony WALKMAN NW-A45 DAC · 7af5a143
    Takashi Iwai authored
    We've got a regression report for USB-audio with Sony WALKMAN NW-A45
    DAC device where no sound is audible on recent kernel.  The bisection
    resulted in the code change wrt endpoint management, and the further
    debug session revealed that it was caused by the order of the USB
    audio interface.  In the earlier code, we always set up the USB
    interface at first before other setups, but it was changed to be done
    at the last for UAC2/3, which is more standard way, while keeping the
    old way for UAC1.  OTOH, this device seems requiring the setup of the
    interface at first just like UAC1.
    
    This patch works around the regression by applying the interface setup
    specifically for the WALKMAN at the beginning of the endpoint setup
    procedure.  This change is written straightforwardly to be easily
    backported in old kernels.  A further cleanup to move the workaround
    into a generic quirk section will follow in a later patch.
    
    Fixes: bf6313a0 ("ALSA: usb-audio: Refactor endpoint management")
    Cc: <stable@vger.kernel.org>
    BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=214105
    Link: https://lore.kernel.org/r/20210824054700.8236-1-tiwai@suse.de
    
    Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
    7af5a143