ALSA: usb - Don't create "Speaker" mixer controls on headphones and headsets

A lot of headsets/headphones have a "Speaker" mixer control. This confuses
PulseAudio to think it is a speaker instead of a headphone/headset.
Therfore, we rename it to "Headphone".

We determine if something is a headphone similar to how udev determines
form factor (see 78-sound-card.rules).

BugLink: https://bugs.launchpad.net/bugs/1082357
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 30 insertions, 0 deletions

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index feed500f943..ed4d89c8b52 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1136,6 +1136,32 @@ static size_t append_ctl_name(struct snd_kcontrol *kctl, const char *str)
         return strlcat(kctl->id.name, str, sizeof(kctl->id.name));
 }
 
+/* A lot of headsets/headphones have a "Speaker" mixer. Make sure we
+   rename it to "Headphone". We determine if something is a headphone
+   similar to how udev determines form factor. */
+static void check_no_speaker_on_headset(struct snd_kcontrol *kctl,
+                                        struct snd_card *card)
+{
+        const char *names_to_check[] = {
+                "Headset", "headset", "Headphone", "headphone", NULL};
+        const char **s;
+        bool found = 0;
+
+        if (strcmp("Speaker", kctl->id.name))
+                return;
+
+        for (s = names_to_check; *s; s++)
+                if (strstr(card->shortname, *s)) {
+                        found = 1;
+                        break;
+                }
+
+        if (!found)
+                return;
+
+        strlcpy(kctl->id.name, "Headphone", sizeof(kctl->id.name));
+}
+
 static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
                               unsigned int ctl_mask, int control,
                               struct usb_audio_term *iterm, int unitid,
@@ -1222,6 +1248,10 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
                                 len = snprintf(kctl->id.name, sizeof(kctl->id.name),
                                                "Feature %d", unitid);
                 }
+
+                if (!mapped_name)
+                        check_no_speaker_on_headset(kctl, state->mixer->chip->card);
+
                 /* determine the stream direction:
                  * if the connected output is USB stream, then it's likely a
                  * capture stream.  otherwise it should be playback (hopefully :)