Re: [BUG] Presonus Studio 1824c firmware 3.11 no longer exposes mixer interface ("Quirk or no altset; falling back to MIDI 1.0")

[Takashi Iwai <tiwai@suse.de>]

On Thu, 16 Oct 2025 17:15:46 +0200,
Pawel / Xj wrote:
> 
> 
> Thanks for answer.
> Unfortunately didn't help. I just checked 6.18rc1.
> The problem is in this "no altset".
> In my previous mail there is analyze that I made with help from ChatGPT :)

Don't trust ChatGPT, seriously...

The "no altset" message comes from USB MIDI2 probe, and the message
itself is neither error nor warning, but informs that it's no MIDI2
but MIDI1 device, and the MIDI1 driver code is used.  So, it's almost
always shown unless the device has a MIDI2 interface.

That said, the message has little to do with the audio mixer problem.

> [  +4,174933] usb 3-2: new high-speed USB device number 3 using xhci_hcd
> [  +0,125582] usb 3-2: New USB device found, idVendor=194f, idProduct=010d,
> bcdDevice= 3.11
> [  +0,000007] usb 3-2: New USB device strings: Mfr=1, Product=3, SerialNumber=
> 2
> [  +0,000001] usb 3-2: Product: Studio 1824c
> [  +0,000001] usb 3-2: Manufacturer: PreSonus
> [  +0,000000] usb 3-2: SerialNumber: SC4E25040072
> [  +0,973997] usb 3-2: Presonus Studio 1810c, device_setup: 0
> [  +0,000006] usb 3-2: (8out/14in @ 96kHz)
> [  +0,278930] usb 3-2: Quirk or no altset; falling back to MIDI 1.0
> 
> I also see something like this
> [  +0,000001] Call Trace:
> [  +0,000002]  <TASK>
> [  +0,000001]  usb_start_wait_urb+0x89/0x190
> [  +0,000002]  usb_control_msg+0xe5/0x150
> [  +0,000002]  snd_usb_ctl_msg+0xa5/0x160
> [  +0,000003]  snd_sc1810c_get_status_field.constprop.0+0xc0/0x140
> [  +0,000005]  snd_s1810c_get_switch_state.constprop.0.isra.0+0x54/0xa0
> [  +0,000002]  snd_s1810c_switch_set+0x69/0x130
> [  +0,000001]  snd_ctl_elem_write+0x18b/0x260
> [  +0,000003]  snd_ctl_ioctl+0x3b8/0x7e0
> [  +0,000002]  __x64_sys_ioctl+0x97/0xe0
> [  +0,000003]  do_syscall_64+0x81/0x7f0
> [  +0,000003]  ? __x64_sys_ioctl+0x97/0xe0
> [  +0,000003]  ? do_syscall_64+0x81/0x7f0
> [  +0,000002]  ? __x64_sys_ioctl+0x97/0xe0
> [  +0,000000]  ? do_syscall_64+0x81/0x7f0
> [  +0,000002]  ? snd_ctl_ioctl+0x20e/0x7e0
> [  +0,000002]  ? __x64_sys_ioctl+0x97/0xe0
> [  +0,000001]  ? do_syscall_64+0x81/0x7f0
> [  +0,000001]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
> [  +0,000002] RIP: 0033:0x7f3da2d112ff

Please give the full content.  It trimmed too much and can't judge
exactly.  I guess it's a problem in the recent quirk code, and it
might not be working well with your firmware.

Roy, could you check whether the recent kernel still works properly
with S1824c?


Takashi