Re: [PATCH] ALSA: usb-audio: Fix Scarlett 8i6 Gen 1 router source numbering

[Takashi Iwai <tiwai@suse.de>]

On Sun, 18 Oct 2026 13:20:09 +0200,
Walter Weber wrote:
> 
> The router source numbering in s8i6_info is identical to the 6i6 entry
> and was never verified on hardware (it is marked "untested..."). On a
> Scarlett 8i6 1st Gen everything after the analog inputs is off by two:
> 
>   - "SPDIF 1/2" select values 16/17, which carry no signal;
>   - "Mix A/B" select values 18/19, which are the actual S/PDIF inputs;
>   - "Mix C-F" select the actual Mix A-D, and Mix E/F cannot be
>     selected at all;
>   - the matrix inputs cannot be fed from S/PDIF.
> 
> The real numbering was measured on the device by routing known signals
> (PCM test tones, mixes with distinct gains, an S/PDIF out-to-in
> loopback) and checking which source value arrives in the capture
> stream:
> 
>   PCM 1-12      0-11
>   Analog 1-4   12-15
>   (no signal)  16-17
>   S/PDIF 1-2   18-19
>   Mix A-F      20-25
> 
> Correct the offsets and enum lengths accordingly, and update the
> (currently unused) matrix_mux_init table to match. Values 16/17
> remain as placeholders (shown as "Analog 5/6") since the enum maps
> items to source values linearly.
> 
> The 6i6 entry uses the same layout and is also marked untested. It is
> left unchanged since I have no 6i6 to verify it.
> 
> Tested on a Scarlett 8i6 1st Gen (bcdDevice 2.60) with v7.2.11.
> 
> Fixes: 76b188c4b370 ("ALSA: usb-audio: Scarlett mixer interface for 6i6, 18i6, 18i8 and 18i20")
> Cc: stable@vger.kernel.org
> Signed-off-by: Walter Weber <walter.weber@rwth-aachen.de>

Applied now.  Thanks.


Takashi