[ALSA] Add error messages

Add error messages in the critial error path to be more verbose.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/control.c b/sound/core/control.c
index 03ae9bb..f8f98cc 100644
--- a/sound/core/control.c
+++ b/sound/core/control.c
@@ -195,8 +195,10 @@
 	snd_assert(control != NULL, return NULL);
 	snd_assert(control->count > 0, return NULL);
 	kctl = kzalloc(sizeof(*kctl) + sizeof(struct snd_kcontrol_volatile) * control->count, GFP_KERNEL);
-	if (kctl == NULL)
+	if (kctl == NULL) {
+		snd_printk(KERN_ERR "Cannot allocate control instance\n");
 		return NULL;
+	}
 	*kctl = *control;
 	for (idx = 0; idx < kctl->count; idx++)
 		kctl->vd[idx].access = access;
@@ -309,7 +311,9 @@
 	struct snd_ctl_elem_id id;
 	unsigned int idx;
 
-	snd_assert(card != NULL && kcontrol != NULL, return -EINVAL);
+	snd_assert(card != NULL, return -EINVAL);
+	if (! kcontrol)
+		return -EINVAL;
 	snd_assert(kcontrol->info != NULL, return -EINVAL);
 	id = kcontrol->id;
 	down_write(&card->controls_rwsem);
diff --git a/sound/core/device.c b/sound/core/device.c
index afa8cc7..b1cf6ec 100644
--- a/sound/core/device.c
+++ b/sound/core/device.c
@@ -50,8 +50,10 @@
 	snd_assert(device_data != NULL, return -ENXIO);
 	snd_assert(ops != NULL, return -ENXIO);
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-	if (dev == NULL)
+	if (dev == NULL) {
+		snd_printk(KERN_ERR "Cannot allocate device\n");
 		return -ENOMEM;
+	}
 	dev->card = card;
 	dev->type = type;
 	dev->state = SNDRV_DEV_BUILD;
@@ -173,6 +175,7 @@
 			dev->state = SNDRV_DEV_REGISTERED;
 			return 0;
 		}
+		snd_printd("snd_device_register busy\n");
 		return -EBUSY;
 	}
 	snd_BUG();
diff --git a/sound/core/hwdep.c b/sound/core/hwdep.c
index da0fb9f..444e266 100644
--- a/sound/core/hwdep.c
+++ b/sound/core/hwdep.c
@@ -364,13 +364,14 @@
 	*rhwdep = NULL;
 	snd_assert(card != NULL, return -ENXIO);
 	hwdep = kzalloc(sizeof(*hwdep), GFP_KERNEL);
-	if (hwdep == NULL)
+	if (hwdep == NULL) {
+		snd_printk(KERN_ERR "hwdep: cannot allocate\n");
 		return -ENOMEM;
+	}
 	hwdep->card = card;
 	hwdep->device = device;
-	if (id) {
+	if (id)
 		strlcpy(hwdep->id, id, sizeof(hwdep->id));
-	}
 #ifdef CONFIG_SND_OSSEMUL
 	hwdep->oss_type = -1;
 #endif
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 59c995b..9305ac3 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -600,14 +600,18 @@
 	pstr->reg = &snd_pcm_reg[stream];
 	if (substream_count > 0) {
 		err = snd_pcm_stream_proc_init(pstr);
-		if (err < 0)
+		if (err < 0) {
+			snd_printk(KERN_ERR "Error in snd_pcm_stream_proc_init\n");
 			return err;
+		}
 	}
 	prev = NULL;
 	for (idx = 0, prev = NULL; idx < substream_count; idx++) {
 		substream = kzalloc(sizeof(*substream), GFP_KERNEL);
-		if (substream == NULL)
+		if (substream == NULL) {
+			snd_printk(KERN_ERR "Cannot allocate PCM substream\n");
 			return -ENOMEM;
+		}
 		substream->pcm = pcm;
 		substream->pstr = pstr;
 		substream->number = idx;
@@ -620,6 +624,7 @@
 			prev->next = substream;
 		err = snd_pcm_substream_proc_init(substream);
 		if (err < 0) {
+			snd_printk(KERN_ERR "Error in snd_pcm_stream_proc_init\n");
 			kfree(substream);
 			return err;
 		}
@@ -666,13 +671,14 @@
 	*rpcm = NULL;
 	snd_assert(card != NULL, return -ENXIO);
 	pcm = kzalloc(sizeof(*pcm), GFP_KERNEL);
-	if (pcm == NULL)
+	if (pcm == NULL) {
+		snd_printk(KERN_ERR "Cannot allocate PCM\n");
 		return -ENOMEM;
+	}
 	pcm->card = card;
 	pcm->device = device;
-	if (id) {
+	if (id)
 		strlcpy(pcm->id, id, sizeof(pcm->id));
-	}
 	if ((err = snd_pcm_new_stream(pcm, SNDRV_PCM_STREAM_PLAYBACK, playback_count)) < 0) {
 		snd_pcm_free(pcm);
 		return err;
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index ede0a60..7a86a9a 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -1382,8 +1382,10 @@
 	INIT_LIST_HEAD(&stream->substreams);
 	for (idx = 0; idx < count; idx++) {
 		substream = kzalloc(sizeof(*substream), GFP_KERNEL);
-		if (substream == NULL)
+		if (substream == NULL) {
+			snd_printk(KERN_ERR "rawmidi: cannot allocate substream\n");
 			return -ENOMEM;
+		}
 		substream->stream = direction;
 		substream->number = idx;
 		substream->rmidi = rmidi;
@@ -1425,19 +1427,27 @@
 	*rrawmidi = NULL;
 	snd_assert(card != NULL, return -ENXIO);
 	rmidi = kzalloc(sizeof(*rmidi), GFP_KERNEL);
-	if (rmidi == NULL)
+	if (rmidi == NULL) {
+		snd_printk(KERN_ERR "rawmidi: cannot allocate\n");
 		return -ENOMEM;
+	}
 	rmidi->card = card;
 	rmidi->device = device;
 	init_MUTEX(&rmidi->open_mutex);
 	init_waitqueue_head(&rmidi->open_wait);
 	if (id != NULL)
 		strlcpy(rmidi->id, id, sizeof(rmidi->id));
-	if ((err = snd_rawmidi_alloc_substreams(rmidi, &rmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT], SNDRV_RAWMIDI_STREAM_INPUT, input_count)) < 0) {
+	if ((err = snd_rawmidi_alloc_substreams(rmidi,
+						&rmidi->streams[SNDRV_RAWMIDI_STREAM_INPUT],
+						SNDRV_RAWMIDI_STREAM_INPUT,
+						input_count)) < 0) {
 		snd_rawmidi_free(rmidi);
 		return err;
 	}
-	if ((err = snd_rawmidi_alloc_substreams(rmidi, &rmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT], SNDRV_RAWMIDI_STREAM_OUTPUT, output_count)) < 0) {
+	if ((err = snd_rawmidi_alloc_substreams(rmidi,
+						&rmidi->streams[SNDRV_RAWMIDI_STREAM_OUTPUT],
+						SNDRV_RAWMIDI_STREAM_OUTPUT,
+						output_count)) < 0) {
 		snd_rawmidi_free(rmidi);
 		return err;
 	}
diff --git a/sound/core/timer.c b/sound/core/timer.c
index 18d43a0..74637ce 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -777,8 +777,10 @@
 	snd_assert(rtimer != NULL, return -EINVAL);
 	*rtimer = NULL;
 	timer = kzalloc(sizeof(*timer), GFP_KERNEL);
-	if (timer == NULL)
+	if (timer == NULL) {
+		snd_printk(KERN_ERR "timer: cannot allocate\n");
 		return -ENOMEM;
+	}
 	timer->tmr_class = tid->dev_class;
 	timer->card = card;
 	timer->tmr_device = tid->device;