ASoC: Ensure we generate a driver name

Commit 873bd4cb (ASoC: Don't set invalid name string to snd_card->driver
field) broke generation of a driver name for all ASoC cards relying on the
automatic generation of one. Fix this by using the old default with spaces
replaced by underscores.
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

sound/soc/soc-core.c

@@ -30,6 +30,7 @@
 #include <linux/bitops.h>
 #include <linux/debugfs.h>
 #include <linux/platform_device.h>
+#include <linux/ctype.h>
 #include <linux/slab.h>
 #include <sound/ac97_codec.h>
 #include <sound/core.h>
@@ -1434,9 +1435,20 @@ static void snd_soc_instantiate_card(struct snd_soc_card *card)
 		 "%s", card->name);
 	snprintf(card->snd_card->longname, sizeof(card->snd_card->longname),
 		 "%s", card->long_name ? card->long_name : card->name);
-	if (card->driver_name)
-		strlcpy(card->snd_card->driver, card->driver_name,
-			sizeof(card->snd_card->driver));
+	snprintf(card->snd_card->driver, sizeof(card->snd_card->driver),
+		 "%s", card->driver_name ? card->driver_name : card->name);
+	for (i = 0; i < ARRAY_SIZE(card->snd_card->driver); i++) {
+		switch (card->snd_card->driver[i]) {
+		case '_':
+		case '-':
+		case '\0':
+			break;
+		default:
+			if (!isalnum(card->snd_card->driver[i]))
+				card->snd_card->driver[i] = '_';
+			break;
+		}
+	}
 
 	if (card->late_probe) {
 		ret = card->late_probe(card);