ALSA: hda - Add probe_only option

Added probe_only module option to hd-audio driver.
This option specifies whether the driver creates and initializes the
codec-parser after probing.  When this option is set, the driver skips
the codec parsing and initialization but gives you proc and other
accesses.  It's useful to see the initial codec state for debugging.

The default of this value is off, so the default behavior is as same
as before.
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Documentation/sound/alsa/ALSA-Configuration.txt

@@ -757,6 +757,8 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed.
     model	- force the model name
     position_fix - Fix DMA pointer (0 = auto, 1 = use LPIB, 2 = POSBUF)
     probe_mask  - Bitmask to probe codecs (default = -1, meaning all slots)
+    probe_only	- Only probing and no codec initialization (default=off);
+		  Useful to check the initial codec status for debugging
     bdl_pos_adj	- Specifies the DMA IRQ timing delay in samples.
 		Passing -1 will make the driver to choose the appropriate
 		value based on the controller chip.

sound/pci/hda/hda_codec.c

@@ -709,7 +709,7 @@ static void snd_hda_codec_free(struct hda_codec *codec)
  * Returns 0 if successful, or a negative error code.
  */
 int /*__devinit*/ snd_hda_codec_new(struct hda_bus *bus, unsigned int codec_addr,
-				struct hda_codec **codecp)
+				    int do_init, struct hda_codec **codecp)
 {
 	struct hda_codec *codec;
 	char component[31];
@@ -793,11 +793,13 @@ int /*__devinit*/ snd_hda_codec_new(struct hda_bus *bus, unsigned int codec_addr
 	if (bus->modelname)
 		codec->modelname = kstrdup(bus->modelname, GFP_KERNEL);
 
+	if (do_init) {
 		err = snd_hda_codec_configure(codec);
 		if (err < 0) {
 			snd_hda_codec_free(codec);
 			return err;
 		}
+	}
 	snd_hda_codec_proc_new(codec);
 
 	snd_hda_create_hwdep(codec);

sound/pci/hda/hda_codec.h

@@ -811,7 +811,7 @@ enum {
 int snd_hda_bus_new(struct snd_card *card, const struct hda_bus_template *temp,
 		    struct hda_bus **busp);
 int snd_hda_codec_new(struct hda_bus *bus, unsigned int codec_addr,
-		      struct hda_codec **codecp);
+		      int do_init, struct hda_codec **codecp);
 
 /*
  * low level functions

sound/pci/hda/hda_intel.c

@@ -58,6 +58,7 @@ static char *model[SNDRV_CARDS];
 static int position_fix[SNDRV_CARDS];
 static int bdl_pos_adj[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS-1)] = -1};
 static int probe_mask[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS-1)] = -1};
+static int probe_only[SNDRV_CARDS];
 static int single_cmd;
 static int enable_msi;
 
@@ -76,6 +77,8 @@ module_param_array(bdl_pos_adj, int, NULL, 0644);
 MODULE_PARM_DESC(bdl_pos_adj, "BDL position adjustment offset.");
 module_param_array(probe_mask, int, NULL, 0444);
 MODULE_PARM_DESC(probe_mask, "Bitmask to probe codecs (default = -1).");
+module_param_array(probe_only, bool, NULL, 0444);
+MODULE_PARM_DESC(probe_only, "Only probing and no codec initialization.");
 module_param(single_cmd, bool, 0444);
 MODULE_PARM_DESC(single_cmd, "Use single command to communicate with codecs "
 		 "(for debugging only).");
@@ -1224,7 +1227,8 @@ static unsigned int azx_max_codecs[AZX_NUM_DRIVERS] __devinitdata = {
 };
 
 static int __devinit azx_codec_create(struct azx *chip, const char *model,
-				      unsigned int codec_probe_mask)
+				      unsigned int codec_probe_mask,
+				      int no_init)
 {
 	struct hda_bus_template bus_temp;
 	int c, codecs, err;
@@ -1282,7 +1286,7 @@ static int __devinit azx_codec_create(struct azx *chip, const char *model,
 	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);
+			err = snd_hda_codec_new(chip->bus, c, !no_init, &codec);
 			if (err < 0)
 				continue;
 			codecs++;
@@ -2340,7 +2344,8 @@ static int __devinit azx_probe(struct pci_dev *pci,
 	card->private_data = chip;
 
 	/* create codec instances */
-	err = azx_codec_create(chip, model[dev], probe_mask[dev]);
+	err = azx_codec_create(chip, model[dev], probe_mask[dev],
+			       probe_only[dev]);
 	if (err < 0)
 		goto out_free;