[PATCH 2/2] ALSA: usb-audio: Set up (implicit) sync for Saffire 6

[Takashi Iwai]

Focusrite Saffire 6 has fixed audioformat quirks with multiple
endpoints assigned to a single altsetting.  Unfortunately the generic
parser couldn't detect the sync endpoint correctly as the implicit
sync due to the missing EP attribute bits.  In the former kernels, it
used to work somehow casually, but it's been broken for a while after
the large code change in 5.11.

This patch cures the regression by the following:
- Allow the static quirk table to provide the sync EP information;
  we just need to fill the fields and let the generic parser skipping
  parsing if sync_ep is already set.
- Add the sync endpoint information to the entry for Saffire 6.

Fixes: 7b0efea4baf0 ("ALSA: usb-audio: Add missing ep_idx in fixed EP quirks")
Reported-and-tested-by: André Kapelrud <a.kapelrud at gmail.com>
Cc: <stable at vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/usb/pcm.c          | 3 +++
 sound/usb/quirks-table.h | 7 ++++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index b0369df53910..e692ae04436a 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -291,6 +291,9 @@ int snd_usb_audioformat_set_sync_ep(struct snd_usb_audio *chip,
 	bool is_playback;
 	int err;
 
+	if (fmt->sync_ep)
+		return 0; /* already set up */
+
 	alts = snd_usb_get_host_interface(chip, fmt->iface, fmt->altsetting);
 	if (!alts)
 		return 0;
diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index 78eb41b621d6..4f56e1784932 100644
--- a/sound/usb/quirks-table.h
+++ b/sound/usb/quirks-table.h
@@ -2658,7 +2658,12 @@ YAMAHA_DEVICE(0x7010, "UB99"),
 					.nr_rates = 2,
 					.rate_table = (unsigned int[]) {
 						44100, 48000
-					}
+					},
+					.sync_ep = 0x82,
+					.sync_iface = 0,
+					.sync_altsetting = 1,
+					.sync_ep_idx = 1,
+					.implicit_fb = 1,
 				}
 			},
 			{
-- 
2.35.3