ALSA: usb-audio: SKIP_IFACE_SETUP regression on Focusrite Scarlett 2i2 (1235:8006)

ALSA: usb-audio: SKIP_IFACE_SETUP regression on Focusrite Scarlett 2i2 (1235:8006)

[Geoffrey D. Bennett]

Hi Takashi,

A user reported distorted/silent audio on 6.19.7 with a Focusrite 1st
Generation Scarlett 2i2 (1235:8006), caused by 38c322068a26 ("ALSA:
usb-audio: Add QUIRK_FLAG_SKIP_IFACE_SETUP").

The Feedback Format (from /proc stream0) changes from 16.16 to 17.15
when SKIP_IFACE_SETUP is enabled. The user confirmed that removing
SKIP_IFACE_SETUP fixes the issue.

This device doesn't have the internal mixer, Air, or Safe modes that
the quirk was designed to protect, so it doesn't benefit from the
skip.

I'm not sure if there's a better fix than explicitly listing all the
devices that I tested?

E.g. replace:

        VENDOR_FLG(0x1235, /* Focusrite Novation */
                   QUIRK_FLAG_SKIP_CLOCK_SELECTOR |
                   QUIRK_FLAG_SKIP_IFACE_SETUP),

with ~23 of these:

        DEVICE_FLG(0x1235, 0x8203, /* Focusrite Scarlett 2nd Gen 6i6 */
                   QUIRK_FLAG_SKIP_CLOCK_SELECTOR |
                   QUIRK_FLAG_SKIP_IFACE_SETUP),

What do you think?

Report: https://github.com/geoffreybennett/linux-fcp/issues/54

Thanks,
Geoffrey.

Re: ALSA: usb-audio: SKIP_IFACE_SETUP regression on Focusrite Scarlett 2i2 (1235:8006)

[Takashi Iwai]

On Sun, 15 Mar 2026 20:20:54 +0100,
Geoffrey D. Bennett wrote:
> 
> Hi Takashi,
> 
> A user reported distorted/silent audio on 6.19.7 with a Focusrite 1st
> Generation Scarlett 2i2 (1235:8006), caused by 38c322068a26 ("ALSA:
> usb-audio: Add QUIRK_FLAG_SKIP_IFACE_SETUP").
> 
> The Feedback Format (from /proc stream0) changes from 16.16 to 17.15
> when SKIP_IFACE_SETUP is enabled. The user confirmed that removing
> SKIP_IFACE_SETUP fixes the issue.
> 
> This device doesn't have the internal mixer, Air, or Safe modes that
> the quirk was designed to protect, so it doesn't benefit from the
> skip.
> 
> I'm not sure if there's a better fix than explicitly listing all the
> devices that I tested?
> 
> E.g. replace:
> 
>         VENDOR_FLG(0x1235, /* Focusrite Novation */
>                    QUIRK_FLAG_SKIP_CLOCK_SELECTOR |
>                    QUIRK_FLAG_SKIP_IFACE_SETUP),
> 
> with ~23 of these:
> 
>         DEVICE_FLG(0x1235, 0x8203, /* Focusrite Scarlett 2nd Gen 6i6 */
>                    QUIRK_FLAG_SKIP_CLOCK_SELECTOR |
>                    QUIRK_FLAG_SKIP_IFACE_SETUP),
> 
> What do you think?
> 
> Report: https://github.com/geoffreybennett/linux-fcp/issues/54

We can put DEVICE_FLG() entries for the known Focusrite devices that
shouldn't to set QUIRK_FLAG_SKIP_IFACE_SETUP before the VENDOR_FLG()
entry that keeps *_SKIP_IFACE_SETUP flag?


thanks,

Takashi