mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-09-02 06:05:42 -04:00
Code Issues Packages Projects Releases Wiki Activity

ALSA: usb-audio: add QUIRK_FLAG_ALWAYS_SET_RATE for Mackie DLZ Creator XS

Browse Source 
set_sample_rate_v2v3() returns early when the clock already reports the
requested rate:

	prev_rate = get_sample_rate_v2v3(chip, fmt->iface,
					 fmt->altsetting, clock);
	if (prev_rate == rate)
		goto validation;

A device advertising exactly one sample rate always takes this branch, so
it never receives a SET_CUR for CS_SAM_FREQ_CONTROL at all.

The Mackie DLZ Creator XS (0a73:003a, 14 in / 4 out, 48 kHz only) requires
that write.  Without it the device drops off the USB bus roughly 0.2-1.8 s
into any stream, clearing its port CONNECTION bit; captured audio is
byte-correct until the instant it vanishes.

USBPcap traces of a cold-booted device on Windows show SET_CUR 48000 issued
unconditionally on every stream start, followed by clean streaming.  The
device is otherwise driven with plain class-compliant UAC2 - it also works
on iOS, which cannot load a vendor driver - so no vendor-specific
initialization is involved.

The device is self-powered, so the resulting state survives a USB replug:
initializing it on any host that issues the write leaves it working on
Linux until it is power-cycled, which made the failure look intermittent.

Add a quirk flag rather than dropping the early exit, since the opposite
requirement also exists in-tree: QUIRK_FLAG_FIXED_RATE suppresses rate
setting for single-rate devices (JBL Quantum610/810).  The two behaviors
are device-dependent and cannot both be the default.

A/B on identically cold-booted hardware, same kernel, same port, repeated
twice:

  without the flag  device dropped after 5-6 s, then again after 3-4 s
  with the flag     20 s playback followed by 20 s of 14-channel capture,
                    960000 frames, zero re-enumerations

This change was developed with an AI coding assistant.  The assistant did
the trace analysis that located the bug and wrote the patch and this
changelog; the hardware testing, the cold-boot cycles and the decision to
submit were the author's.  Several earlier hypotheses it proposed - URB
queue depth, isochronous packet under-allocation, endpoint start ordering -
were disproven by measurement before this one.

The bug was located with usbmon on Linux and USBPcap on Windows, by
diffing an enumeration capture of a cold-booted device on each host.
Verified on physical hardware by the A/B above.

Assisted-by: Claude-Code:claude-opus-5
Signed-off-by: JJ Macalinao <jj@macalinao.org>
Link: https://patch.msgid.link/20260808172726.1107550-1-jj@macalinao.org
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
JJ Macalinao
2026-08-09 01:27:26 +08:00
committed by Takashi Iwai
parent 8a906c0b4f
commit 786f91da85
3 changed files with 16 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
sound/usb/clock.c
View File

@@ -600,7 +600,7 @@ int snd_usb_set_sample_rate_v2v3(struct snd_usb_audio *chip,
static int set_sample_rate_v2v3(struct snd_usb_audio *chip,
const struct audioformat *fmt, int rate)
{
int cur_rate, prev_rate;
int cur_rate, prev_rate = 0;
int clock;
/* First, try to find a valid clock. This may trigger
@@ -625,9 +625,12 @@ static int set_sample_rate_v2v3(struct snd_usb_audio *chip,
return clock;
}
prev_rate = get_sample_rate_v2v3(chip, fmt->iface, fmt->altsetting, clock);
if (prev_rate == rate)
goto validation;
if (!(chip->quirk_flags & QUIRK_FLAG_ALWAYS_SET_RATE)) {
prev_rate = get_sample_rate_v2v3(chip, fmt->iface,
fmt->altsetting, clock);
if (prev_rate == rate)
goto validation;
}
cur_rate = snd_usb_set_sample_rate_v2v3(chip, fmt, clock, rate);
if (cur_rate < 0) {

3
sound/usb/quirks.c
View File

@@ -2333,6 +2333,8 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = {
QUIRK_FLAG_IGNORE_CTL_ERROR),
DEVICE_FLG(0x0951, 0x16ad, /* Kingston HyperX */
QUIRK_FLAG_CTL_MSG_DELAY_1M),
DEVICE_FLG(0x0a73, 0x003a, /* Mackie DLZ Creator XS */
QUIRK_FLAG_ALWAYS_SET_RATE),
DEVICE_FLG(0x0b05, 0x18a6, /* ASUSTek Computer, Inc. */
QUIRK_FLAG_MIXER_CAPTURE_MIN_MUTE),
DEVICE_FLG(0x0b0e, 0x0349, /* Jabra 550a */
@@ -2638,6 +2640,7 @@ static const char *const snd_usb_audio_quirk_flag_names[] = {
QUIRK_STRING_ENTRY(IFB_SILENCE_ON_EMPTY),
QUIRK_STRING_ENTRY(MIXER_GET_CUR_BROKEN),
QUIRK_STRING_ENTRY(PLAYBACK_URB_FIXUP),
QUIRK_STRING_ENTRY(ALWAYS_SET_RATE),
NULL
};

6
sound/usb/usbaudio.h
View File

@@ -260,6 +260,10 @@ extern bool snd_usb_skip_validation;
* to insufficient buffer depth combined with xHCI scheduling variability.
* The larger buffer (MAX_URBS = 12, ~64ms) absorbs system scheduling
* jitter during boot, while URB_ISO_ASAP ensures consistent xHCI scheduling.
* QUIRK_FLAG_ALWAYS_SET_RATE:
* Issue SET_CUR for the sample rate even when the clock already reports the
* requested rate. A device advertising a single rate is otherwise never sent
* the request at all, and some require it before streaming will start.
*/
enum {
@@ -295,6 +299,7 @@ enum {
QUIRK_TYPE_IFB_SILENCE_ON_EMPTY = 29,
QUIRK_TYPE_MIXER_GET_CUR_BROKEN = 30,
QUIRK_TYPE_PLAYBACK_URB_FIXUP = 31,
QUIRK_TYPE_ALWAYS_SET_RATE = 32,
/* Please also edit snd_usb_audio_quirk_flag_names */
};
@@ -332,5 +337,6 @@ enum {
#define QUIRK_FLAG_IFB_SILENCE_ON_EMPTY QUIRK_FLAG(IFB_SILENCE_ON_EMPTY)
#define QUIRK_FLAG_MIXER_GET_CUR_BROKEN QUIRK_FLAG(MIXER_GET_CUR_BROKEN)
#define QUIRK_FLAG_PLAYBACK_URB_FIXUP QUIRK_FLAG(PLAYBACK_URB_FIXUP)
#define QUIRK_FLAG_ALWAYS_SET_RATE QUIRK_FLAG(ALWAYS_SET_RATE)
#endif /* __USBAUDIO_H */