Re: [PATCH] ALSA: usb-audio: add Pioneer DJ DDJ-SZ support

[Geraldo Nascimento]

Hi everyone,

On Thu, Sep 3, 2026 at 8:18 PM Hanh Kieu <hhkieu@xxxxxxxxx> wrote:
>
> The Pioneer DJ DDJ-SZ exposes its audio interface as USB vendor-specific
> class (0xFF) rather than USB Audio Class, so it needs a quirks-table
> entry like its sibling Pioneer devices (DJM-750, DJM-850, DJM-900NXS2,
> DJM-450, DJM-V10) already have.
>
> The device presents 10 channels of S24_3LE audio in both directions,
> fixed at 44.1kHz, on interface 0 altsetting 1: playback on endpoint
> 0x01, capture on endpoint 0x82. The unit contains its own analog mixer,
> and each playback channel pair feeds one of its physical channel strips:
> 0/1, 2/3, 4/5 and 6/7 feed strips 1-4 respectively, and 8/9 feed the
> booth output. The master output is produced in analog by that mixer and
> is not carried over USB at all. On the capture side, channels 8/9 are
> the mic input; capture channels 0-7 are not yet mapped to specific
> physical inputs.
>
> Implicit feedback needs no quirk flag here: is_pioneer_implicit_fb() in
> implicit.c already covers vendor 0x08e4 with a vendor-spec class
> interface and two endpoints, and the driver duly reports endpoint 0x82
> as the playback sync endpoint.

Are you sure is_pioneer_implicit_fb() isn't returning false and you're
picking up on a generic sync ep instead?

You should double-check that function is returning true or false because it
will return false when USB_ENDPOINT_USAGE_IMPLICIT_FB isn't
set on bmAttributes of a Isochronous IN EP.

Thanks,
Geraldo Nascimento