[PATCH 4.4 129/143] ALSA: usb-audio: Fix implicit fb endpoint setup by quirk

From: Greg Kroah-Hartman
Date: Mon Feb 18 2019 - 09:19:53 EST


4.4-stable review patch. If anyone has any objections, please let me know.

------------------

From: Manuel Reinhardt <manuel.rhdt@xxxxxxxxx>

commit 2bc16b9f3223d049b57202ee702fcb5b9b507019 upstream.

The commit a60945fd08e4 ("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: a60945fd08e4 ("ALSA: usb-audio: move implicit fb quirks to separate function")
Signed-off-by: Manuel Reinhardt <manuel.rhdt@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
sound/usb/pcm.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)

--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -313,6 +313,9 @@ static int search_roland_implicit_fb(str
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_
if (err < 0)
return err;

+ /* endpoint set by quirk */
+ if (err > 0)
+ return 0;
+
if (altsd->bNumEndpoints < 2)
return 0;