[PATCH 4.19 023/103] ALSA: dice: fix fallback from protocol extension into limited functionality

[Greg Kroah-Hartman]

From: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>

commit 3e2dc6bdb56893bc28257e482e1dbe5d39f313df upstream.

At failure of attempt to detect protocol extension, ALSA dice driver
should be fallback to limited functionality. However it's not.

This commit fixes it.

Cc: <stable@xxxxxxxxxxxxxxx> # v4.18+
Fixes: 58579c056c1c9 ("ALSA: dice: use extended protocol to detect available stream formats")
Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200113084630.14305-2-o-takashi@xxxxxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 sound/firewire/dice/dice-extension.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/sound/firewire/dice/dice-extension.c
+++ b/sound/firewire/dice/dice-extension.c
@@ -159,8 +159,11 @@ int snd_dice_detect_extension_formats(st
 		int j;
 
 		for (j = i + 1; j < 9; ++j) {
-			if (pointers[i * 2] == pointers[j * 2])
+			if (pointers[i * 2] == pointers[j * 2]) {
+				// Fallback to limited functionality.
+				err = -ENXIO;
 				goto end;
+			}
 		}
 	}