ALSA: hda - Fix "PCM" name being used on one DAC when there are two DACs

In the scenario where there is one "Line Out", one "Speaker" and one
"Headphone", and there are only two DACs, two outputs will share a DAC.
Currently any mixer on such a DAC will get the "PCM" name, which is
misleading. Instead use "Headphone+LO" or "Speaker+LO" to better
specify what the volume actually controls.

[fixed missing slave string additions by tiwai]
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_generic.c

@@ -1038,6 +1038,19 @@ static const char *get_line_out_pfx(struct hda_codec *codec, int ch,
 			break;
 		*index = ch;
 		return "Headphone";
+	case AUTO_PIN_LINE_OUT:
+		/* This deals with the case where we have two DACs and
+		 * one LO, one HP and one Speaker */
+		if (!ch && cfg->speaker_outs && cfg->hp_outs) {
+			bool hp_lo_shared = !path_has_mixer(codec, spec->hp_paths[0], ctl_type);
+			bool spk_lo_shared = !path_has_mixer(codec, spec->speaker_paths[0], ctl_type);
+			if (hp_lo_shared && spk_lo_shared)
+				return spec->vmaster_mute.hook ? "PCM" : "Master";
+			if (hp_lo_shared)
+				return "Headphone+LO";
+			if (spk_lo_shared)
+				return "Speaker+LO";
+		}
 	}
 
 	/* for a single channel output, we don't have to name the channel */
@@ -4524,7 +4537,7 @@ static const char * const slave_pfxs[] = {
 	"CLFE", "Bass Speaker", "PCM",
 	"Speaker Front", "Speaker Surround", "Speaker CLFE", "Speaker Side",
 	"Headphone Front", "Headphone Surround", "Headphone CLFE",
-	"Headphone Side",
+	"Headphone Side", "Headphone+LO", "Speaker+LO",
 	NULL,
 };