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

[Takashi Iwai <tiwai@suse.de>]

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