Commit 05268b5c authored by Manuel Reinhardt's avatar Manuel Reinhardt Committed by Greg Kroah-Hartman

ALSA: usb-audio: Fix implicit fb endpoint setup by quirk

commit 2bc16b9f3223d049b57202ee702fcb5b9b507019 upstream.

The commit a60945fd ("ALSA: usb-audio: move implicit fb quirks to
separate function") introduced an error in the handling of quirks for
implicit feedback endpoints. This commit fixes this.

If a quirk successfully sets up an implicit feedback endpoint, usb-audio
no longer tries to find the implicit fb endpoint itself.

Fixes: a60945fd ("ALSA: usb-audio: move implicit fb quirks to separate function")
Signed-off-by: default avatarManuel Reinhardt <>
Cc: <>
Signed-off-by: default avatarTakashi Iwai <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 422e1adf
......@@ -313,6 +313,9 @@ static int search_roland_implicit_fb(struct usb_device *dev, int ifnum,
return 0;
/* Setup an implicit feedback endpoint from a quirk. Returns 0 if no quirk
* applies. Returns 1 if a quirk was found.
static int set_sync_ep_implicit_fb_quirk(struct snd_usb_substream *subs,
struct usb_device *dev,
struct usb_interface_descriptor *altsd,
......@@ -381,7 +384,7 @@ add_sync_ep:
subs->data_endpoint->sync_master = subs->sync_endpoint;
return 0;
return 1;
static int set_sync_endpoint(struct snd_usb_substream *subs,
......@@ -420,6 +423,10 @@ static int set_sync_endpoint(struct snd_usb_substream *subs,
if (err < 0)
return err;
/* endpoint set by quirk */
if (err > 0)
return 0;
if (altsd->bNumEndpoints < 2)
return 0;
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