[PATCH] ALSA: usb-audio: Explicitly set up the clock selector

[Takashi Iwai]

In the current code, we have some assumption that the audio clock
selector has been set up implicitly and don't want to touch it unless
it's really needed for the fallback autoclock setup.  This works for
most devices but some seem having a problem.  Partially this was
covered for the devices with a single connector at the initialization
phase (commit 086b957cc17f "ALSA: usb-audio: Skip the clock selector
inquiry for single connections"), but also there are cases where the
wrong clock set up is kept silently.  The latter seems to be the cause
of the noises on Behringer devices.

In this patch, we explicitly set up the audio clock selector whenever
the appropriate node is found.

Reported-by: Geraldo Nascimento <geraldogabriel at gmail.com>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=199327
Link: https://lore.kernel.org/r/CAEsQvcvF7LnO8PxyyCxuRCx=7jNeSCvFAd-+dE0g_rd1rOxxdw@mail.gmail.com
Cc: <stable at vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/usb/clock.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/sound/usb/clock.c b/sound/usb/clock.c
index a746802d0ac3..17bbde73d4d1 100644
--- a/sound/usb/clock.c
+++ b/sound/usb/clock.c
@@ -296,7 +296,7 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
 
 	selector = snd_usb_find_clock_selector(chip->ctrl_intf, entity_id);
 	if (selector) {
-		int ret, i, cur;
+		int ret, i, cur, err;
 
 		if (selector->bNrInPins == 1) {
 			ret = 1;
@@ -324,13 +324,17 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip,
 		ret = __uac_clock_find_source(chip, fmt,
 					      selector->baCSourceID[ret - 1],
 					      visited, validate);
+		if (ret > 0) {
+			err = uac_clock_selector_set_val(chip, entity_id, cur);
+			if (err < 0)
+				return err;
+		}
+
 		if (!validate || ret > 0 || !chip->autoclock)
 			return ret;
 
 		/* The current clock source is invalid, try others. */
 		for (i = 1; i <= selector->bNrInPins; i++) {
-			int err;
-
 			if (i == cur)
 				continue;
 
@@ -396,7 +400,7 @@ static int __uac3_clock_find_source(struct snd_usb_audio *chip,
 
 	selector = snd_usb_find_clock_selector_v3(chip->ctrl_intf, entity_id);
 	if (selector) {
-		int ret, i, cur;
+		int ret, i, cur, err;
 
 		/* the entity ID we are looking for is a selector.
 		 * find out what it currently selects */
@@ -418,6 +422,12 @@ static int __uac3_clock_find_source(struct snd_usb_audio *chip,
 		ret = __uac3_clock_find_source(chip, fmt,
 					       selector->baCSourceID[ret - 1],
 					       visited, validate);
+		if (ret > 0) {
+			err = uac_clock_selector_set_val(chip, entity_id, cur);
+			if (err < 0)
+				return err;
+		}
+
 		if (!validate || ret > 0 || !chip->autoclock)
 			return ret;
 
-- 
2.26.2