Re: [PATCH] usb-audio: Fix boot-time crackling for Generic USB Audio device

[Takashi Iwai <tiwai@suse.de>]

On Tue, 14 Jul 2026 15:09:46 +0200,
Zhang Heng wrote:
> 
> 
> From 11c25cb49a0a233fda643b2eb6c0bca7bc726d37 Mon Sep 17 00:00:00 2001
> From: Zhang Heng <zhangheng@kylinos.cn>
> Date: Tue, 14 Jul 2026 17:55:54 +0800
> Subject: [PATCH] ALSA: usb-audio: Fix boot-time crackling for Generic USB
>  Audio device
> 
> The Generic USB Audio device (0x1e0b:d01e) produces crackling noise during
> system boot when the boot music plays. The issue disappears once the system
> has fully started.
> 
> Kernel logs show xhci-ring warnings when the device initializes:
> [    9.654586] xhci_hcd 0000:03:00.3: Frame ID 644 (reg 5154, index 13) beyond range (645, 1539)
> [    9.654589] xhci_hcd 0000:03:00.3: Ignore frame ID field, use SIA bit instead
> [    9.655053] xhci_hcd 0000:03:00.3: Frame ID 644 (reg 5158, index 14) beyond range (645, 1539)
> [    9.655055] xhci_hcd 0000:03:00.3: Ignore frame ID field, use SIA bit instead
> 
> These warnings indicate that xhci_get_isoc_frame_id() returns -EINVAL for
> TDs at index > 0 because their calculated Frame IDs become stale before
> validation completes. This causes a fallback to SIA mode for those TDs,
> while index=0 TD uses direct Frame ID. The resulting mixed scheduling within
> the same data endpoint causes audio data misalignment and crackling.
> 
> Fix by adding QUIRK_FLAG_ISO_ASAP and setting URB_ISO_ASAP flag for the
> data endpoint. This ensures all TDs use consistent SIA scheduling. Also add
> a quirk to skip the first 4 sync packets, as some devices send incorrect
> feedback data during stream startup.
> 
> Using the quirk mechanism keeps endpoint.c device-agnostic and allows easy
> addition of new devices with the same symptom.
> 
> Signed-off-by: Zhang Heng <zhangheng@kylinos.cn>
> ---
> v1->v2:
>  
> - Replace hardcoded USB ID check in endpoint.c with QUIRK_FLAG_ISO_ASAP
> - Add QUIRK_TYPE_ISO_ASAP = 31 enum and QUIRK_FLAG_ISO_ASAP macro in usbaudio.h
> - Add device entry to quirk_flags_table in quirks.c for Generic USB Audio (0x1e0b:d01e)
> - Add ISO_ASAP string entry to snd_usb_audio_quirk_flag_names
> - Add documentation comment for QUIRK_FLAG_ISO_ASAP in usbaudio.h
> - Keep endpoint.c device-agnostic, allowing easy addition of new devices
> 
>  sound/usb/endpoint.c | 2 ++
>  sound/usb/quirks.c   | 8 ++++++++
>  sound/usb/usbaudio.h | 8 ++++++++
>  3 files changed, 18 insertions(+)
> 
> diff --git a/sound/usb/endpoint.c b/sound/usb/endpoint.c
> index 24cd7692bd01..155b3858dac9 100644
> --- a/sound/usb/endpoint.c
> +++ b/sound/usb/endpoint.c
> @@ -1256,6 +1256,8 @@ static int data_ep_set_params(struct snd_usb_endpoint *ep)
>  			goto out_of_memory;
>  		u->urb->pipe = ep->pipe;
>  		u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
> +		if (ep->chip->quirk_flags & QUIRK_FLAG_ISO_ASAP)
> +			u->urb->transfer_flags |= URB_ISO_ASAP;
>  		u->urb->interval = 1 << ep->datainterval;
>  		u->urb->context = u;
>  		u->urb->complete = snd_complete_urb;
> diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
> index 2949a0d2d961..f5e5b662bfd3 100644
> --- a/sound/usb/quirks.c
> +++ b/sound/usb/quirks.c
> @@ -1938,6 +1938,10 @@ void snd_usb_endpoint_start_quirk(struct snd_usb_endpoint *ep)
>  	    ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
>  		ep->skip_packets = 4;
>  
> +	if (ep->chip->usb_id == USB_ID(0x1e0b, 0xd01e) &&
> +	    ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
> +		ep->skip_packets = 4;
> +

Please add some comment why the device needs this workaround.
IIUC, the reason is different from the others in your case.

Also, please verify that the problem is reproduced in the latest
upstream kernel, and the workaround works as expected there, too.


thanks,

Takashi