From 9df28edce7c6ab38050235f6f8b43dd7ccd01b6d Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Fri, 18 Dec 2020 15:58:58 +0100
Subject: [PATCH] ALSA: usb-audio: Disable sample read check if firmware doesn't give back
Git-commit: 9df28edce7c6ab38050235f6f8b43dd7ccd01b6d
Patch-mainline: v5.11-rc1
References: git-fixes

Some buggy firmware don't give the current sample rate but leaves
zero.  Handle this case more gracefully without warning but just skip
the current rate verification from the next time.

Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201218145858.2357-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/usb/clock.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index e940dcee792b..31051f2be46d 100644
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -534,6 +534,12 @@ static int set_sample_rate_v1(struct snd_usb_audio *chip,
 	}
 
 	crate = data[0] | (data[1] << 8) | (data[2] << 16);
+	if (!crate) {
+		dev_info(&dev->dev, "failed to read current rate; disabling the check\n");
+		chip->sample_rate_read_error = 3; /* three strikes, see above */
+		return 0;
+	}
+
 	if (crate != rate) {
 		dev_warn(&dev->dev, "current rate %d is different from the runtime rate %d\n", crate, rate);
 		// runtime->rate = crate;
-- 
2.26.2