alsa-mixer: Allow selected fallback mappings in all profile sets

When fallback mapping is selected all subsequent profile sets containing
selected mapping are ignored. When there are only e.g. fallback input mappings
available, admitted profile set will only contain one profile with selected
first input fallback mapping and no outputs, and rest of profiles will only
contain outputs and no inputs. When there are only fallback input and output
mappings, there will be no profiles admitted at all.

Fix this by making sure that selected first fallback input or output mapping
is actually allowed to exist in all probed profile sets.

Note while this change allows selected fallback mappings to be found in duplex
configuraitons, probing fallbacks still can fail if there is more than one input
fallback and first one (selected) does not work in duplex configurations.

Part-of: <https://gitlab.freedesktop.org/pulseaudio/pulseaudio/-/merge_requests/539>

1 files changed, 15 insertions, 3 deletions

diff --git a/src/modules/alsa/alsa-mixer.c b/src/modules/alsa/alsa-mixer.c
index 0bbac262e..c29ab966c 100644
--- a/src/modules/alsa/alsa-mixer.c
+++ b/src/modules/alsa/alsa-mixer.c
@@ -5151,6 +5151,7 @@ void pa_alsa_profile_set_probe(
     pa_alsa_profile **pp, **probe_order;
     pa_alsa_mapping *m;
     pa_hashmap *broken_inputs, *broken_outputs, *used_paths;
+    pa_alsa_mapping *selected_fallback_input = NULL, *selected_fallback_output = NULL;
 
     pa_assert(ps);
     pa_assert(dev_id);
@@ -5173,11 +5174,16 @@ void pa_alsa_profile_set_probe(
         uint32_t idx;
         p = *pp;
 
-        /* Skip if fallback and already found something */
+        /* Skip if fallback and already found something, but still probe already selected fallbacks.
+         * If UCM is used then both fallback_input and fallback_output flags are false.
+         * If UCM is not used then there will be only a single entry in mappings.
+         */
         if (found_input && p->fallback_input)
-            continue;
+            if (selected_fallback_input == NULL || pa_idxset_get_by_index(p->input_mappings, 0) != selected_fallback_input)
+                continue;
         if (found_output && p->fallback_output)
-            continue;
+            if (selected_fallback_output == NULL || pa_idxset_get_by_index(p->output_mappings, 0) != selected_fallback_output)
+                continue;
 
         /* Skip if this is already marked that it is supported (i.e. from the config file) */
         if (!p->supported) {
@@ -5269,6 +5275,9 @@ void pa_alsa_profile_set_probe(
             PA_IDXSET_FOREACH(m, p->output_mappings, idx)
                 if (m->output_pcm) {
                     found_output = true;
+                    if (p->fallback_output && selected_fallback_output == NULL) {
+                        selected_fallback_output = m;
+                    }
                     mapping_paths_probe(m, p, PA_ALSA_DIRECTION_OUTPUT, used_paths, mixers);
                 }
 
@@ -5276,6 +5285,9 @@ void pa_alsa_profile_set_probe(
             PA_IDXSET_FOREACH(m, p->input_mappings, idx)
                 if (m->input_pcm) {
                     found_input = true;
+                    if (p->fallback_input && selected_fallback_input == NULL) {
+                        selected_fallback_input = m;
+                    }
                     mapping_paths_probe(m, p, PA_ALSA_DIRECTION_INPUT, used_paths, mixers);
                 }
     }