[PATCH 5.15 214/247] ALSA: usb-audio: Skip generic sync EP parse for secondary EP

[Greg Kroah-Hartman]

From: Takashi Iwai <tiwai@xxxxxxx>

commit efb75df105e82f076a85b9f2d81410428bcb55fc upstream.

When ep_idx is already non-zero, it means usually a capture stream
that is set up explicity by a fixed-format quirk, and applying the
check for generic (non-implicit-fb) sync EPs might hit incorrectly,
resulting in a bogus sync endpoint for the capture stream.

This patch adds a check for the ep_idx and skip if it's a secondary
endpoint.  It's a part of the fixes for regressions on Saffire 6.

Fixes: 7b0efea4baf0 ("ALSA: usb-audio: Add missing ep_idx in fixed EP quirks")
Reported-and-tested-by: André Kapelrud <a.kapelrud@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220606160910.6926-2-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 sound/usb/pcm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index b470404a5376..b0369df53910 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -304,7 +304,7 @@ int snd_usb_audioformat_set_sync_ep(struct snd_usb_audio *chip,
 	 * Generic sync EP handling
 	 */
 
-	if (altsd->bNumEndpoints < 2)
+	if (fmt->ep_idx > 0 || altsd->bNumEndpoints < 2)
 		return 0;
 
 	is_playback = !(get_endpoint(alts, 0)->bEndpointAddress & USB_DIR_IN);
-- 
2.36.1