[PATCH 1/2] ALSA: usb-audio: Skip reading sample rate on M-Audio Venom

[Federico Valentín Andrade]

The M-Audio Venom (0763:2084) is an USB Audio Class 1 compliant
synth with an integrated audio interface, it does not implement
GET_CUR on SAMPLING_FREQ_CONTROL, hanging up if requested on
endpoint 0.

The first class request issued by the driver after enumeration is
a GET_CUR on endpoint 0x02, freezing the device's USB microcontroller.
Timing out on every transfer afterwards with -ETIMEDOUT, such as
SET_INTERFACE, so neither the mixer nor any streaming interface is set up.

Analyzing a USBPcap capture of the Windows driver I found it never
requests the sampling frequency, as the synth exposes a single
discrete of 44100Hz on both streaming interfaces, thus asking for it
is unnecessary.

So I applied get_sample_rate to avoid this check, and
disable_autosuspend because the synth doesn't come back from being
suspended.

Signed-off-by: Federico Valentín Andrade <fandrade@xxxxxxxxxxxxxxx>
---
 sound/usb/quirks.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index f4e1eac639..caa80487f4 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -2334,6 +2334,8 @@ static const struct usb_audio_quirk_flags_table quirk_flags_table[] = {
 		   QUIRK_FLAG_MIXER_GET_CUR_BROKEN | QUIRK_FLAG_GENERIC_IMPLICIT_FB),
 	DEVICE_FLG(0x0763, 0x2081, /* M-Audio Fast Track Ultra */
 		   QUIRK_FLAG_MIXER_GET_CUR_BROKEN | QUIRK_FLAG_GENERIC_IMPLICIT_FB),
+	DEVICE_FLG(0x0763, 0x2084, /* M-Audio Venom */
+		   QUIRK_FLAG_MIXER_GET_SAMPLE_RATE | QUIRK_FLAG_DISABLE_AUTOSUSPEND),
 	DEVICE_FLG(0x07fd, 0x000b, /* MOTU M Series 2nd hardware revision */
 		   QUIRK_FLAG_CTL_MSG_DELAY_1M),
 	DEVICE_FLG(0x08bb, 0x2702, /* LineX FM Transmitter */
-- 
2.55.0