ASoC: Fix double addition of prefixes due to widget prefixing

We're not only prefixing all controls, we're also prefixing the widget
names in the runtime data. This causes us to add the prefix twice - once
when using the widget name to generate the control name and once when
adding the control.

Really we shouldn't be prefixing the widget names at all, the matching
code should be handing this as we always know which DAPM context a
widget came from and always display the widget name in terms of a DAPM
context. However, we're quite close to the merge window and that's
relatively invasive.

Signed-off-by: Mark Brown <[e-mail]>
Reported-by: Jarkko Nikula <[e-mail]>
Acked-by: Jarkko Nikula <[e-mail]>
Acked-by: Liam Girdwood <[e-mail]>

sound/soc/soc-dapm.c

···
 	struct snd_soc_dapm_widget *w)
 {
 	int i, ret = 0;
-	size_t name_len;
+	size_t name_len, prefix_len;
 	struct snd_soc_dapm_path *path;
 	struct snd_card *card = dapm->card->snd_card;
 	const char *prefix;
···
 		prefix = dapm->codec->name_prefix;
 	else
 		prefix = NULL;
+
+	if (prefix)
+		prefix_len = strlen(prefix) + 1;
+	else
+		prefix_len = 0;
 
 	/* add kcontrol */
 	for (i = 0; i < w->num_kcontrols; i++) {
···
 
 			switch (w->id) {
 			default:
+				/* The control will get a prefix from
+				 * the control creation process but
+				 * we're also using the same prefix
+				 * for widgets so cut the prefix off
+				 * the front of the widget name.
+				 */
 				snprintf(path->long_name, name_len, "%s %s",
-					 w->name, w->kcontrols[i].name);
+					 w->name + prefix_len,
+					 w->kcontrols[i].name);
 				break;
 			case snd_soc_dapm_mixer_named_ctl:
 				snprintf(path->long_name, name_len, "%s",
···
 	struct snd_kcontrol *kcontrol;
 	struct snd_card *card = dapm->card->snd_card;
 	const char *prefix;
+	size_t prefix_len;
 	int ret = 0;
 
 	if (!w->num_kcontrols) {
···
 	else
 		prefix = NULL;
 
-	kcontrol = snd_soc_cnew(&w->kcontrols[0], w, w->name, prefix);
+	if (prefix)
+		prefix_len = strlen(prefix) + 1;
+	else
+		prefix_len = 0;
+
+	/* The control will get a prefix from the control creation
+	 * process but we're also using the same prefix for widgets so
+	 * cut the prefix off the front of the widget name.
+	 */
+	kcontrol = snd_soc_cnew(&w->kcontrols[0], w, w->name + prefix_len,
+				prefix);
 	ret = snd_ctl_add(card, kcontrol);
 
 	if (ret < 0)