From fe773b8711e3be4190994ea54bf7a5a0564245a1 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Sat, 23 Jan 2021 16:58:42 +0100
Subject: [PATCH] ALSA: usb-audio: workaround for iface reset issue
Git-commit: fe773b8711e3be4190994ea54bf7a5a0564245a1
Patch-mainline: v5.11-rc6
References: bsc#1178203
The recently introduced sample rate validation code seems causing a
problem on some devices; namely, after performing this, the bus gets
screwed and it influences even on other USB devices.
As a quick workaround, perform it only for the necessary devices;
currently MOTU devices are known to need the valid altset checks, so
filter out other devices.
Fixes: 93db51d06b32 ("ALSA: usb-audio: Check valid altsetting at parsing rates for UAC2/3")
Reported-by: Jamie Heilman <jamie@audible.transient.net>
Buglink: https://bugzilla.suse.com/show_bug.cgi?id=1178203
Link: https://lore.kernel.org/r/20210123155842.22652-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
sound/usb/format.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/sound/usb/format.c b/sound/usb/format.c
index 9ebc5d202c87..e6ff317a6785 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -466,6 +466,17 @@ static int validate_sample_rate_table_v2v3(struct snd_usb_audio *chip,
unsigned int nr_rates;
int i, err;
+ /* performing the rate verification may lead to unexpected USB bus
+ * behavior afterwards by some unknown reason. Do this only for the
+ * known devices.
+ */
+ switch (USB_ID_VENDOR(chip->usb_id)) {
+ case 0x07fd: /* MOTU */
+ break;
+ default:
+ return 0; /* don't perform the validation as default */
+ }
+
table = kcalloc(fp->nr_rates, sizeof(*table), GFP_KERNEL);
if (!table)
return -ENOMEM;
--
2.26.2