[pulseaudio-discuss] [PATCH v2 1/3] alsa-mixer: add hw_device_index to pa_alsa_mapping

[Tanu Kaskinen]

We have so far assumed that HDMI always uses device indexes 3, 7, 8, 9,
10, 11, 12 and 13. These values are hardcoded in the path configuration.
The Intel HDMI LPE driver, however, uses different device numbering
scheme. Since the indexes aren't always the same, we need to query the
hw device index from ALSA.

Later patches will use the queried index for HDMI jack detection and ELD
information reading.

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=100488
---
 src/modules/alsa/alsa-mixer.c | 26 ++++++++++++++++++++++++++
 src/modules/alsa/alsa-mixer.h |  4 ++++
 2 files changed, 30 insertions(+)

diff --git a/src/modules/alsa/alsa-mixer.c b/src/modules/alsa/alsa-mixer.c
index 7de1c7deb..02ab4a611 100644
--- a/src/modules/alsa/alsa-mixer.c
+++ b/src/modules/alsa/alsa-mixer.c
@@ -3505,6 +3505,7 @@ pa_alsa_mapping *pa_alsa_mapping_get(pa_alsa_profile_set *ps, const char *name)
     pa_sample_spec_init(&m->sample_spec);
     pa_channel_map_init(&m->channel_map);
     m->proplist = pa_proplist_new();
+    m->hw_device_index = -1;
 
     pa_hashmap_put(ps->mappings, m->name, m);
 
@@ -4532,6 +4533,25 @@ static int add_profiles_to_probe(
     return i;
 }
 
+static void mapping_query_hw_device(pa_alsa_mapping *mapping, snd_pcm_t *pcm) {
+    int r;
+    snd_pcm_info_t* pcm_info;
+    snd_pcm_info_alloca(&pcm_info);
+
+    r = snd_pcm_info(pcm, pcm_info);
+    if (r < 0) {
+        pa_log("Mapping %s: snd_pcm_info() failed %s: ", mapping->name, pa_alsa_strerror(r));
+        return;
+    }
+
+    /* XXX: It's not clear what snd_pcm_info_get_device() does if the device is
+     * not backed by a hw device or if it's backed by multiple hw devices. We
+     * only use hw_device_index for HDMI devices, however, and for those the
+     * return value is expected to be always valid, so this shouldn't be a
+     * significant problem. */
+    mapping->hw_device_index = snd_pcm_info_get_device(pcm_info);
+}
+
 void pa_alsa_profile_set_probe(
         pa_alsa_profile_set *ps,
         const char *dev_id,
@@ -4622,6 +4642,9 @@ void pa_alsa_profile_set_probe(
                         }
                         break;
                     }
+
+                    if (m->hw_device_index < 0)
+                        mapping_query_hw_device(m, m->output_pcm);
                 }
 
             if (p->input_mappings && p->supported)
@@ -4643,6 +4666,9 @@ void pa_alsa_profile_set_probe(
                         }
                         break;
                     }
+
+                    if (m->hw_device_index < 0)
+                        mapping_query_hw_device(m, m->input_pcm);
                 }
 
             last = p;
diff --git a/src/modules/alsa/alsa-mixer.h b/src/modules/alsa/alsa-mixer.h
index 4ebf1922b..cb482906b 100644
--- a/src/modules/alsa/alsa-mixer.h
+++ b/src/modules/alsa/alsa-mixer.h
@@ -275,6 +275,10 @@ struct pa_alsa_mapping {
     bool exact_channels:1;
     bool fallback:1;
 
+    /* The "y" in "hw:x,y". This is set to -1 before the device index has been
+     * queried, or if the query failed. */
+    int hw_device_index;
+
     /* Temporarily used during probing */
     snd_pcm_t *input_pcm;
     snd_pcm_t *output_pcm;
-- 
2.14.2