pulseaudio/0001-alsa-mixer-allow-to-re-attach-the-mixer-control-elem.patch

From def8eb074eb4a80836c39fa320c33fe89bce38d9 Mon Sep 17 00:00:00 2001
From: Jaroslav Kysela <perex@perex.cz>
Date: Mon, 27 Jun 2022 10:32:07 +0200
Subject: [PATCH] alsa-mixer: allow to re-attach the mixer control element

It may be possible that the ALSA control element appears
again. Allow this combination by checking, if the pulseaudio
mixer element already exists. Do not create the duplicate
mixer element in this case.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/729>
---
 src/modules/alsa/alsa-util.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/modules/alsa/alsa-util.c b/src/modules/alsa/alsa-util.c
index f4e838d37..81dc77cc3 100644
--- a/src/modules/alsa/alsa-util.c
+++ b/src/modules/alsa/alsa-util.c
@@ -1663,12 +1663,20 @@ static int mixer_class_event(snd_mixer_class_t *class, unsigned int mask,
     } else if (mask & SND_CTL_EVENT_MASK_ADD) {
         snd_ctl_elem_iface_t iface = snd_hctl_elem_get_interface(helem);
         if (iface == SND_CTL_ELEM_IFACE_CARD || iface == SND_CTL_ELEM_IFACE_PCM) {
+            snd_mixer_t *mixer = snd_mixer_class_get_mixer(class);
+            snd_ctl_elem_iface_t iface = snd_hctl_elem_get_interface(helem);
+            const char *name = snd_hctl_elem_get_name(helem);
+            const int index = snd_hctl_elem_get_index(helem);
+            const int device = snd_hctl_elem_get_device(helem);
             snd_mixer_elem_t *new_melem;
-
-            /* Put the hctl pointer as our private data - it will be useful for callbacks */
-            if ((err = snd_mixer_elem_new(&new_melem, SND_MIXER_ELEM_PULSEAUDIO, 0, helem, NULL)) < 0) {
-                pa_log_warn("snd_mixer_elem_new failed: %s", pa_alsa_strerror(err));
-                return 0;
+ 
+            new_melem = pa_alsa_mixer_find(mixer, iface, name, index, device);
+            if (!new_melem) {
+                /* Put the hctl pointer as our private data - it will be useful for callbacks */
+                if ((err = snd_mixer_elem_new(&new_melem, SND_MIXER_ELEM_PULSEAUDIO, 0, helem, NULL)) < 0) {
+                    pa_log_warn("snd_mixer_elem_new failed: %s", pa_alsa_strerror(err));
+                    return 0;
+                }
             }
 
             if ((err = snd_mixer_elem_attach(new_melem, helem)) < 0) {
-- 
2.33.0