alsa: Allow sample spec override in mappings

This allows mappings to override some or all of the sample_spec used to
open the ALSA device. The intention, to start with, is to use this for
devices in UCM that need to be opened at a specific rate (like modem
devices). This can be extended to allow overrides in profile-sets as
well.

src/modules/alsa/alsa-mixer.c

@@ -3368,6 +3368,7 @@ pa_alsa_mapping *pa_alsa_mapping_get(pa_alsa_profile_set *ps, const char *name)
     m = pa_xnew0(pa_alsa_mapping, 1);
     m->profile_set = ps;
     m->name = pa_xstrdup(name);
+    pa_sample_spec_init(&m->sample_spec);
     pa_channel_map_init(&m->channel_map);
     m->proplist = pa_proplist_new();
 

src/modules/alsa/alsa-mixer.h

@@ -251,6 +251,7 @@ struct pa_alsa_mapping {
     /* These are copied over to the resultant sink/source */
     pa_proplist *proplist;
 
+    pa_sample_spec sample_spec;
     pa_channel_map channel_map;
 
     char **device_strings;

src/modules/alsa/alsa-sink.c

@@ -2030,6 +2030,19 @@ pa_sink *pa_alsa_sink_new(pa_module *m, pa_modargs *ma, const char*driver, pa_ca
 
     ss = m->core->default_sample_spec;
     map = m->core->default_channel_map;
+
+    /* Pick sample spec overrides from the mapping, if any */
+    if (mapping->sample_spec.format != PA_SAMPLE_INVALID)
+        ss.format = mapping->sample_spec.format;
+    if (mapping->sample_spec.rate != 0)
+        ss.rate = mapping->sample_spec.rate;
+    if (mapping->sample_spec.channels != 0) {
+        ss.channels = mapping->sample_spec.channels;
+        if (pa_channel_map_valid(&mapping->channel_map))
+            pa_assert(pa_channel_map_compatible(&mapping->channel_map, &ss));
+    }
+
+    /* Override with modargs if provided */
     if (pa_modargs_get_sample_spec_and_channel_map(ma, &ss, &map, PA_CHANNEL_MAP_ALSA) < 0) {
         pa_log("Failed to parse sample specification and channel map");
         goto fail;

src/modules/alsa/alsa-source.c

@@ -1740,6 +1740,19 @@ pa_source *pa_alsa_source_new(pa_module *m, pa_modargs *ma, const char*driver, p
 
     ss = m->core->default_sample_spec;
     map = m->core->default_channel_map;
+
+    /* Pick sample spec overrides from the mapping, if any */
+    if (mapping->sample_spec.format != PA_SAMPLE_INVALID)
+        ss.format = mapping->sample_spec.format;
+    if (mapping->sample_spec.rate != 0)
+        ss.rate = mapping->sample_spec.rate;
+    if (mapping->sample_spec.channels != 0) {
+        ss.channels = mapping->sample_spec.channels;
+        if (pa_channel_map_valid(&mapping->channel_map))
+            pa_assert(pa_channel_map_compatible(&mapping->channel_map, &ss));
+    }
+
+    /* Override with modargs if provided */
     if (pa_modargs_get_sample_spec_and_channel_map(ma, &ss, &map, PA_CHANNEL_MAP_ALSA) < 0) {
         pa_log("Failed to parse sample specification and channel map");
         goto fail;