The SMSL USB DAC with USB ID 152a:85dd produces an audible pop
when snd-usb-audio performs its redundant probe-time interface setup.
It also pops when returning from runtime suspend.

Skip the probe-time interface setup and disable runtime autosuspend for
this device. Both flags have been verified through the quirk_flags module
parameter.

Keep QUIRK_FLAG_DSD_RAW in the device entry because the exact match takes
precedence over the generic 0x152a vendor entry from which the device
currently inherits that flag.

Signed-off-by: Edward Blair <edward.blair@gmail.com>
---
 sound/usb/quirks.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index eb1750def..eca86b62c 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -2393,6 +2393,9 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = {
 		   QUIRK_FLAG_IFB_SILENCE_ON_EMPTY),
 	DEVICE_FLG(0x13e5, 0x0001, /* Serato Phono */
 		   QUIRK_FLAG_IGNORE_CTL_ERROR),
+	DEVICE_FLG(0x152a, 0x85dd, /* SMSL USB DAC */
+		   QUIRK_FLAG_DSD_RAW | QUIRK_FLAG_DISABLE_AUTOSUSPEND |
+		   QUIRK_FLAG_SKIP_IFACE_SETUP),
 	DEVICE_FLG(0x152a, 0x880a, /* NeuralDSP Quad Cortex */
 		   0), /* Doesn't have the vendor quirk which would otherwise apply */
 	DEVICE_FLG(0x1532, 0x055e, /* Razer Nommo V2 X */
-- 
2.55.0

On Sat, 22 Aug 2026 13:41:10 +0200,
Edward Blair wrote:
> 
> The SMSL USB DAC with USB ID 152a:85dd produces an audible pop
> when snd-usb-audio performs its redundant probe-time interface setup.
> It also pops when returning from runtime suspend.
> 
> Skip the probe-time interface setup and disable runtime autosuspend for
> this device. Both flags have been verified through the quirk_flags module
> parameter.
> 
> Keep QUIRK_FLAG_DSD_RAW in the device entry because the exact match takes
> precedence over the generic 0x152a vendor entry from which the device
> currently inherits that flag.
> 
> Signed-off-by: Edward Blair <edward.blair@gmail.com>

Applied now.  Thanks.


Takashi