[pulseaudio-discuss] [PATCH] alsa-card: improve the profile availability logic

[Tanu Kaskinen]

When a new card shows up (during pulseaudio startup or hotplugged),
pulseaudio needs to pick the initial profile for the card. Unavailable
profiles shouldn't be picked, but module-alsa-card sometimes marked
unavailable profiles as available, causing bad initial profile choices.

This patch changes module-alsa-card so that it marks all profiles
unavailable whose all output ports or all input ports are unavailable.
Previously only those profiles were marked as unavailable whose all
ports were unavailable. For example, if a profile contains one sink and
one source, and the sink is unavailable and the source is available,
previously such profile was marked as available, but now it's marked as
unavailable.

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=102902
---
 src/modules/alsa/module-alsa-card.c | 62 +++++++++++++++++++++++++++++++------
 1 file changed, 52 insertions(+), 10 deletions(-)

diff --git a/src/modules/alsa/module-alsa-card.c b/src/modules/alsa/module-alsa-card.c
index 4f1236ecd..2adfa6d7b 100644
--- a/src/modules/alsa/module-alsa-card.c
+++ b/src/modules/alsa/module-alsa-card.c
@@ -427,29 +427,71 @@ static int report_jack_state(snd_mixer_elem_t *melem, unsigned int mask) {
         if (tp->avail == PA_AVAILABLE_NO)
            pa_device_port_set_available(tp->port, tp->avail);
 
-    /* Update profile availabilities. The logic could be improved; for now we
-     * only set obviously unavailable profiles (those that contain only
-     * unavailable ports) to PA_AVAILABLE_NO and all others to
-     * PA_AVAILABLE_UNKNOWN. */
+    /* Update profile availabilities. Ideally we would mark all profiles
+     * unavailable that contain unavailable devices. We can't currently do that
+     * in all cases, because if there are multiple sinks in a profile, and the
+     * profile contains a mix of available and unavailable ports, we don't know
+     * how the ports are distributed between the different sinks. It's possible
+     * that some sinks contain only unavailable ports, in which case we should
+     * mark the profile as unavailable, but it's also possible that all sinks
+     * contain at least one available port, in which case we should mark the
+     * profile as available. Until the data structures are improved so that we
+     * can distinguish between these two cases, we mark the problematic cases
+     * as available (well, "unknown" to be precise, but there's little
+     * practical difference).
+     *
+     * When all output ports are unavailable, we know that all sinks are
+     * unavailable, and therefore the profile is marked unavailable as well.
+     * The same applies to input ports as well, of course.
+     *
+     * If there are no output ports at all, but the profile contains at least
+     * one sink, then the output is considered to be available. */
     PA_HASHMAP_FOREACH(profile, u->card->profiles, state) {
         pa_device_port *port;
         void *state2;
-        pa_available_t available = PA_AVAILABLE_NO;
+        bool all_output_ports_are_unavailable = false;
+        bool all_input_ports_are_unavailable = false;
+        pa_available_t available = PA_AVAILABLE_UNKNOWN;
 
-        /* Don't touch the "off" profile. */
-        if (profile->n_sources == 0 && profile->n_sinks == 0)
-            continue;
+        /* Check if all output ports are unavailable. */
+        PA_HASHMAP_FOREACH(port, u->card->ports, state2) {
+            if (port->direction != PA_DIRECTION_OUTPUT)
+                continue;
+
+            if (!pa_hashmap_get(port->profiles, profile->name))
+                continue;
 
+            if (port->available == PA_AVAILABLE_NO)
+                all_output_ports_are_unavailable = true;
+            else {
+                all_output_ports_are_unavailable = false;
+                break;
+            }
+        }
+
+        /* Check if all input ports are unavailable. */
         PA_HASHMAP_FOREACH(port, u->card->ports, state2) {
+            if (port->direction != PA_DIRECTION_INPUT)
+                continue;
+
             if (!pa_hashmap_get(port->profiles, profile->name))
                 continue;
 
-            if (port->available != PA_AVAILABLE_NO) {
-                available = PA_AVAILABLE_UNKNOWN;
+            if (port->available == PA_AVAILABLE_NO)
+                all_input_ports_are_unavailable = true;
+            else {
+                all_input_ports_are_unavailable = false;
                 break;
             }
         }
 
+        if (all_output_ports_are_unavailable || all_input_ports_are_unavailable)
+            available = PA_AVAILABLE_NO;
+
+        /* The "off" profile is always available. */
+        if (profile->n_sources == 0 && profile->n_sinks == 0)
+            available = PA_AVAILABLE_YES;
+
         pa_card_profile_set_available(profile, available);
     }
 
-- 
2.14.1