ALSA: hda - Get rid of magic digits for subdev hack

Define a proper const for a magic 31bit flag for subdev / NID setup
with a brief comment.

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

sound/pci/hda/hda_codec.c

@@ -1523,7 +1523,7 @@ int snd_hda_ctl_add(struct hda_codec *codec, hda_nid_t nid,
 	int err;
 	struct hda_nid_item *item;
 
-	if (kctl->id.subdevice & (1<<31)) {
+	if (kctl->id.subdevice & HDA_SUBDEV_NID_FLAG) {
 		if (nid == 0)
 			nid = kctl->id.subdevice & 0xffff;
 		kctl->id.subdevice = 0;

sound/pci/hda/hda_local.h

@@ -23,6 +23,15 @@
 #ifndef __SOUND_HDA_LOCAL_H
 #define __SOUND_HDA_LOCAL_H
 
+/* We abuse kcontrol_new.subdev field to pass the NID corresponding to
+ * the given new control.  If id.subdev has a bit flag HDA_SUBDEV_NID_FLAG,
+ * snd_hda_ctl_add() takes the lower-bit subdev value as a valid NID.
+ * 
+ * Note that the subdevice field is cleared again before the real registration
+ * in snd_hda_ctl_add(), so that this value won't appear in the outside.
+ */
+#define HDA_SUBDEV_NID_FLAG	(1U << 31)
+
 /*
  * for mixer controls
  */
@@ -33,7 +42,7 @@
 /* mono volume with index (index=0,1,...) (channel=1,2) */
 #define HDA_CODEC_VOLUME_MONO_IDX(xname, xcidx, nid, channel, xindex, direction) \
 	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .index = xcidx,  \
-	  .subdevice = (1<<31)|(nid), \
+	  .subdevice = HDA_SUBDEV_NID_FLAG | (nid), \
 	  .access = SNDRV_CTL_ELEM_ACCESS_READWRITE | \
 	  	    SNDRV_CTL_ELEM_ACCESS_TLV_READ | \
 	  	    SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK, \
@@ -54,7 +63,7 @@
 /* mono mute switch with index (index=0,1,...) (channel=1,2) */
 #define HDA_CODEC_MUTE_MONO_IDX(xname, xcidx, nid, channel, xindex, direction) \
 	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .index = xcidx, \
-	  .subdevice = (1<<31)|(nid), \
+	  .subdevice = HDA_SUBDEV_NID_FLAG | (nid), \
 	  .info = snd_hda_mixer_amp_switch_info, \
 	  .get = snd_hda_mixer_amp_switch_get, \
 	  .put = snd_hda_mixer_amp_switch_put, \
@@ -71,7 +80,7 @@
 /* special beep mono mute switch with index (index=0,1,...) (channel=1,2) */
 #define HDA_CODEC_MUTE_BEEP_MONO_IDX(xname, xcidx, nid, channel, xindex, direction) \
 	{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .index = xcidx, \
-	  .subdevice = (1<<31)|(nid), \
+	  .subdevice = HDA_SUBDEV_NID_FLAG | (nid), \
 	  .info = snd_hda_mixer_amp_switch_info, \
 	  .get = snd_hda_mixer_amp_switch_get, \
 	  .put = snd_hda_mixer_amp_switch_put_beep, \

sound/pci/hda/patch_analog.c

@@ -2572,7 +2572,7 @@ static int add_control(struct ad198x_spec *spec, int type, const char *name,
 	if (! knew->name)
 		return -ENOMEM;
 	if (get_amp_nid_(val))
-		knew->subdevice = (1<<31)|get_amp_nid_(val);
+		knew->subdevice = HDA_SUBDEV_NID_FLAG | get_amp_nid_(val);
 	knew->private_value = val;
 	return 0;
 }

sound/pci/hda/patch_realtek.c

@@ -4324,7 +4324,7 @@ static int add_control(struct alc_spec *spec, int type, const char *name,
 	if (!knew->name)
 		return -ENOMEM;
 	if (get_amp_nid_(val))
-		knew->subdevice = (1<<31)|get_amp_nid_(val);
+		knew->subdevice = HDA_SUBDEV_NID_FLAG | get_amp_nid_(val);
 	knew->private_value = val;
 	return 0;
 }

sound/pci/hda/patch_sigmatel.c

@@ -2689,7 +2689,7 @@ stac_control_new(struct sigmatel_spec *spec,
 		return NULL;
 	}
 	if (nid)
-		knew->subdevice = (1<<31)|nid;
+		knew->subdevice = HDA_SUBDEV_NID_FLAG | nid;
 	return knew;
 }
 

sound/pci/hda/patch_via.c

@@ -443,7 +443,7 @@ static int via_add_control(struct via_spec *spec, int type, const char *name,
 	if (!knew->name)
 		return -ENOMEM;
 	if (get_amp_nid_(val))
-		knew->subdevice = (1<<31)|get_amp_nid_(val);
+		knew->subdevice = HDA_SUBDEV_NID_FLAG | get_amp_nid_(val);
 	knew->private_value = val;
 	return 0;
 }