Re: [REGRESSION 6.14 -> 7.0] ALSA snd-ctxfi: no PCM playback on Creative X-Fi Titanium HD (EMU20k2 / SB1270)

[Takashi Iwai <tiwai@suse.de>]

On Mon, 28 Sep 2026 01:51:04 +0200,
Dany Patoine wrote:
> 
> Hello,
> 
> I am reporting a playback regression in the snd-ctxfi driver affecting a
> Creative Sound Blaster X-Fi Titanium HD. The card works perfectly on kernel
> 6.14 but produces no audible PCM playback on kernel 7.0.
> 
> HARDWARE
> - Card:   Creative Sound Blaster X-Fi Titanium HD (model SB1270)
> - Chip:   EMU20k2 / CA20K2
> - PCI:    02:00.0 Audio device [0403]: Creative Labs EMU20k2
>           [Sound Blaster X-Fi Titanium Series] [1102:000b] (rev 03)
> - Driver: snd_ctxfi (with module option use_system_timer=1)
> - System: ASUS P8H67-M PRO, Intel Core i5-2400, x86_64
> 
> SOFTWARE
> - Distribution: Linux Mint 22.3 (Ubuntu 24.04 "noble" base)
> - Sound server: PipeWire + WirePlumber
> - WORKS:  kernel 6.14.0-37-generic  (Ubuntu HWE)
> - BROKEN: kernel 7.0.0-31-generic and 7.0.0-34-generic (Ubuntu HWE 7.0)
> 
> SYMPTOM
> On 7.0, PCM playback produces no audible output, through BOTH paths:
> 
>   (a) Direct ALSA, bypassing PipeWire:
>         speaker-test -D plughw:CARD=XFi,DEV=0 -c 2 -t sine -f 440
>       completes with exit code 0, but no sound is produced.
> 
>   (b) The normal PipeWire path (default sink = the X-Fi):
>       also completely silent.
> 
> Details of the failure mode:
>   - kernel 7.0.0-31: truncated / choppy fragments with use_system_timer=1,
>     and total silence with use_system_timer=0.
>   - kernel 7.0.0-34: total silence with use_system_timer=1.
>   - No xrun and no error is logged; playback appears to stall silently.
> 
> On kernel 6.14.0-37, the exact same commands and configuration
> (use_system_timer=1) produce clean, continuous audio.
> 
> RULED OUT (all verified while booted on the failing 7.0 kernel)
>   - Card detection: OK. snd_ctxfi loads without error; `aplay -l` lists
>     card "XFi [Creative X-Fi]" with all PCM devices (Front/WaveIn,
>     Surround, Center/LFE, Side, IEC958 Non-audio).
>   - Mixer / routing: Master 98%, PCM 100% (no playback mute), Front [on]
>     100%, "Analog Output" = Speakers. PipeWire's default sink is the X-Fi
>     at 94% and is not muted.
>   - use_system_timer: both values tested (0 and 1), neither gives
>     continuous sound on 7.0.
> 
> RELATION TO A KNOWN FIX
> This appears to be DISTINCT from the EMU20k2 regression fixed by commit
> e9418da50d9e ("ALSA: ctxfi: Limit PTP to a single page"): that issue only
> affected PulseAudio while direct ALSA (speaker-test) kept working. Here,
> direct ALSA is ALSO silent, so it looks like a different problem.
> 
> WHAT I CAN PROVIDE
> These kernels are Ubuntu-packaged, not vanilla mainline. On request I can:
>   - provide full dmesg from a 7.0 boot and `alsa-info.sh` output,
>   - test a vanilla mainline 7.0.x / 7.1.x kernel,
>   - test any candidate patch,
>   - perform a git bisect between 6.14 and 7.0 if that would help.

Could you verify the latest 7.3-rc5 kernel to see whether the
regression is still present at first?  If the bug is still there,
please go bisection.


thanks,

Takashi