From: Takashi Iwai <tiwai@suse.de>
Subject: ALSA: hda - Make codec-probing more robust
Patch-mainline: 2.6.29-rc1
References: bnc#502733

When an error occurs during the codec probing, typically accessing to an
non-existing codec slot, the controller chip gets often screwed up and
can no longer communicate with the codecs.

This patch adds a preparation phase just to probe codec addresses before
actually creating codec instances.  If any error occurs during this
probing phase, the driver resets the controller to recover.

This will (hopefully) fix the famous "single_cmd" errors.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/pci/hda/hda_intel.c |   88 ++++++++++++++++++++++++++++++----------------
 1 file changed, 59 insertions(+), 29 deletions(-)

--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -392,6 +392,7 @@ struct azx {
 	unsigned int msi :1;
 	unsigned int irq_pending_warned :1;
 	unsigned int via_dmapos_patch :1; /* enable DMA-position fix for VIA */
+	unsigned int probing :1; /* codec probing phase */
 
 	/* for debugging */
 	unsigned int last_cmd;	/* last issued command (to sync) */
@@ -624,6 +625,14 @@ static unsigned int azx_rirb_get_respons
 		goto again;
 	}
 
+	if (chip->probing) {
+		/* If this critical timeout happens during the codec probing
+		 * phase, this is likely an access to a non-existing codec
+		 * slot.  Better to return an error and reset the system.
+		 */
+		return -1;
+	}
+
 	snd_printk(KERN_ERR "hda_intel: azx_get_response timeout, "
 		   "switching to single_cmd mode: last cmd=0x%08x\n",
 		   chip->last_cmd);
@@ -1178,6 +1187,26 @@ static int azx_setup_controller(struct a
 	return 0;
 }
 
+/*
+ * Probe the given codec address
+ */
+static int probe_codec(struct azx *chip, int addr)
+{
+	unsigned int cmd = (addr << 28) | (AC_NODE_ROOT << 20) |
+		(AC_VERB_PARAMETERS << 8) | AC_PAR_VENDOR_ID;
+	unsigned int res;
+
+	chip->probing = 1;
+	azx_send_cmd(chip->bus, cmd);
+	res = azx_get_response(chip->bus);
+	chip->probing = 0;
+	if (res == -1)
+		return -EIO;
+	snd_printdd("hda_intel: codec #%d probed OK\n", addr);
+	return 0;
+}
+
+static void azx_stop_chip(struct azx *chip);
 
 /*
  * Codec initialization
@@ -1188,21 +1217,12 @@ static unsigned int azx_max_codecs[AZX_N
 	[AZX_DRIVER_TERA] = 1,
 };
 
-/* number of slots to probe as default
- * this can be different from azx_max_codecs[] -- e.g. some boards
- * report wrongly the non-existing 4th slot availability
- */
-static unsigned int azx_default_codecs[AZX_NUM_DRIVERS] __devinitdata = {
-	[AZX_DRIVER_ICH] = 3,
-	[AZX_DRIVER_ATI] = 3,
-};
-
 static int __devinit azx_codec_create(struct azx *chip, const char *model,
 				      unsigned int codec_probe_mask)
 {
 	struct hda_bus_template bus_temp;
-	int c, codecs, audio_codecs, err;
-	int def_slots, max_slots;
+	int c, codecs, err;
+	int max_slots;
 
 	memset(&bus_temp, 0, sizeof(bus_temp));
 	bus_temp.private_data = chip;
@@ -1221,33 +1241,43 @@ static int __devinit azx_codec_create(st
 	if (chip->driver_type == AZX_DRIVER_NVIDIA)
 		chip->bus->needs_damn_long_delay = 1;
 
-	codecs = audio_codecs = 0;
+	codecs = 0;
 	max_slots = azx_max_codecs[chip->driver_type];
 	if (!max_slots)
 		max_slots = AZX_MAX_CODECS;
-	def_slots = azx_default_codecs[chip->driver_type];
-	if (!def_slots)
-		def_slots = max_slots;
-	for (c = 0; c < def_slots; c++) {
+
+	/* First try to probe all given codec slots */
+	for (c = 0; c < max_slots; c++) {
+		if ((chip->codec_mask & (1 << c)) & codec_probe_mask) {
+			if (probe_codec(chip, c) < 0) {
+				/* Some BIOSen give you wrong codec addresses
+				 * that don't exist
+				 */
+				snd_printk(KERN_WARNING
+					   "hda_intel: Codec #%d probe error; "
+					   "disabling it...\n", c);
+				chip->codec_mask &= ~(1 << c);
+				/* More badly, accessing to a non-existing
+				 * codec often screws up the controller chip,
+				 * and distrubs the further communications.
+				 * Thus if an error occurs during probing,
+				 * better to reset the controller chip to
+				 * get back to the sanity state.
+				 */
+				azx_stop_chip(chip);
+				azx_init_chip(chip);
+			}
+		}
+	}
+
+	/* Then create codec instances */
+	for (c = 0; c < max_slots; c++) {
 		if ((chip->codec_mask & (1 << c)) & codec_probe_mask) {
 			struct hda_codec *codec;
 			err = snd_hda_codec_new(chip->bus, c, &codec);
 			if (err < 0)
 				continue;
 			codecs++;
-			if (codec->afg)
-				audio_codecs++;
-		}
-	}
-	if (!audio_codecs) {
-		/* probe additional slots if no codec is found */
-		for (; c < max_slots; c++) {
-			if ((chip->codec_mask & (1 << c)) & codec_probe_mask) {
-				err = snd_hda_codec_new(chip->bus, c, NULL);
-				if (err < 0)
-					continue;
-				codecs++;
-			}
 		}
 	}
 	if (!codecs) {