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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 5.16 135/227] ALSA: usb-audio: Dont abort resume upon errors
Date:   Mon, 21 Feb 2022 09:49:14 +0100
Message-Id: <20220221084939.341918784@linuxfoundation.org>
In-Reply-To: <20220221084934.836145070@linuxfoundation.org>
References: <20220221084934.836145070@linuxfoundation.org>
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From: Takashi Iwai <tiwai@suse.de>

commit 9a5adeb28b77416446658e75bdef3bbe5fb92a83 upstream.

The default mixer resume code treats the errors at restoring the
modified mixer items as a fatal error, and it returns back to the
caller.  This ends up in the resume failure, and the device will be
come unavailable, although basically those errors are intermittent and
can be safely ignored.

The problem itself has been present from the beginning, but it didn't
hit usually because the code tries to resume only the modified items.
But now with the recent commit to forcibly initialize each item at the
probe time, the problem surfaced more often, hence it appears as a
regression.

This patch fixes the regression simply by ignoring the errors at
resume.

Fixes: b96681bd5827 ("ALSA: usb-audio: Initialize every feature unit once at probe time")
Cc: <stable@vger.kernel.org>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215561
Link: https://lore.kernel.org/r/20220214125711.20531-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/usb/mixer.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -3678,17 +3678,14 @@ static int restore_mixer_value(struct us
 				err = snd_usb_set_cur_mix_value(cval, c + 1, idx,
 							cval->cache_val[idx]);
 				if (err < 0)
-					return err;
+					break;
 			}
 			idx++;
 		}
 	} else {
 		/* master */
-		if (cval->cached) {
-			err = snd_usb_set_cur_mix_value(cval, 0, 0, *cval->cache_val);
-			if (err < 0)
-				return err;
-		}
+		if (cval->cached)
+			snd_usb_set_cur_mix_value(cval, 0, 0, *cval->cache_val);
 	}
 
 	return 0;