[pulseaudio-discuss] [PATCH] alsa: Don't try to use ELD controls with UCM

Tanu Kaskinen tanu.kaskinen at linux.intel.com
Fri Feb 6 14:15:34 PST 2015

This fixes a crash that occurred when trying to access non-existent
port data. Doing this:

    pa_alsa_port_data *data = PA_DEVICE_PORT_DATA(port);

is not a good idea when using UCM, because in the UCM mode ports don't
have any data, so the data pointer points to some random memory.
 src/modules/alsa/module-alsa-card.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/modules/alsa/module-alsa-card.c b/src/modules/alsa/module-alsa-card.c
index df04155..a7fec04 100644
--- a/src/modules/alsa/module-alsa-card.c
+++ b/src/modules/alsa/module-alsa-card.c
@@ -455,6 +455,12 @@ static void init_eld_ctls(struct userdata *u) {
     if (!u->mixer_handle)
+    /* The code in this function expects ports to have a pa_alsa_port_data
+     * struct as their data, but in UCM mode ports don't have any data. Hence,
+     * the ELD controls can't currently be used in UCM mode. */
+    if (u->use_ucm)
+        return;
     PA_HASHMAP_FOREACH(port, u->card->ports, state) {
         pa_alsa_port_data *data = PA_DEVICE_PORT_DATA(port);
         snd_mixer_elem_t* melem;

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