alsa: if we are passed a UCM device, make sure to open UCM

UCM devices can require local data from use_case_mgr_open() but since
we do that in a separate process, make sure we reopen the use case
manager in case we are passed a UCM device so that the config is
available.

See #1251

spa/plugins/alsa/alsa-pcm-sink.c

@@ -724,6 +724,7 @@ static int impl_clear(struct spa_handle *handle)
 	spa_return_val_if_fail(handle != NULL, -EINVAL);
 	this = (struct state *) handle;
 	spa_alsa_close(this);
+	spa_alsa_clear(this);
 	return 0;
 }
 
@@ -805,8 +806,6 @@ impl_init(const struct spa_handle_factory *factory,
 
 	spa_list_init(&this->ready);
 
-	snd_config_update_free_global();
-
 	for (i = 0; info && i < info->n_items; i++) {
 		const char *k = info->items[i].key;
 		const char *s = info->items[i].value;
@@ -834,7 +833,8 @@ impl_init(const struct spa_handle_factory *factory,
 			this->props.use_chmap = spa_atob(s);
 		}
 	}
-	return 0;
+
+	return spa_alsa_init(this);
 }
 
 static const struct spa_interface_info impl_interfaces[] = {

spa/plugins/alsa/alsa-pcm-source.c

@@ -744,6 +744,7 @@ static int impl_clear(struct spa_handle *handle)
 	spa_return_val_if_fail(handle != NULL, -EINVAL);
 	this = (struct state *) handle;
 	spa_alsa_close(this);
+	spa_alsa_clear(this);
 	return 0;
 }
 
@@ -823,8 +824,6 @@ impl_init(const struct spa_handle_factory *factory,
 	spa_list_init(&this->free);
 	spa_list_init(&this->ready);
 
-	snd_config_update_free_global();
-
 	for (i = 0; info && i < info->n_items; i++) {
 		const char *k = info->items[i].key;
 		const char *s = info->items[i].value;
@@ -850,7 +849,7 @@ impl_init(const struct spa_handle_factory *factory,
 			this->props.use_chmap = spa_atob(s);
 		}
 	}
-	return 0;
+	return spa_alsa_init(this);
 }
 
 static const struct spa_interface_info impl_interfaces[] = {

spa/plugins/alsa/alsa-pcm.c

@@ -15,6 +15,29 @@
 
 #include "alsa-pcm.h"
 
+int spa_alsa_init(struct state *state)
+{
+	int err;
+
+	snd_config_update_free_global();
+
+	if (strncmp(state->props.device, "_ucm", 4) == 0 &&
+	    strlen(state->props.device) >= 12 &&
+	    state->props.device[8] == '.') {
+		if ((err = snd_use_case_mgr_open(&state->ucm, &state->props.device[9])) < 0)
+			return err;
+	}
+	return 0;
+}
+
+int spa_alsa_clear(struct state *state)
+{
+	if (state->ucm)
+		snd_use_case_mgr_close(state->ucm);
+	state->ucm = NULL;
+	return 0;
+}
+
 #define CHECK(s,msg,...) if ((err = (s)) < 0) { spa_log_error(state->log, msg ": %s", ##__VA_ARGS__, snd_strerror(err)); return err; }
 
 int spa_alsa_open(struct state *state)

spa/plugins/alsa/alsa-pcm.h

@@ -33,6 +33,7 @@ extern "C" {
 #include <math.h>
 
 #include <alsa/asoundlib.h>
+#include <alsa/use-case.h>
 
 #include <spa/support/plugin.h>
 #include <spa/support/loop.h>
@@ -194,6 +195,8 @@ struct state {
 	double max_error;
 
 	struct spa_latency_info latency;
+
+	snd_use_case_mgr_t *ucm;
 };
 
 int
@@ -203,6 +206,9 @@ spa_alsa_enum_format(struct state *state, int seq,
 
 int spa_alsa_set_format(struct state *state, struct spa_audio_info *info, uint32_t flags);
 
+int spa_alsa_init(struct state *state);
+int spa_alsa_clear(struct state *state);
+
 int spa_alsa_open(struct state *state);
 int spa_alsa_start(struct state *state);
 int spa_alsa_reassign_follower(struct state *state);