[ALSA] PCM core - introduce CONFIG_SND_PCM_XRUN_DEBUG

This patch makes the XRUN (overrun/underrun) notification code optional.
Signed-off-by: Jaroslav Kysela <perex@suse.cz>

sound/core/Kconfig

@@ -171,3 +171,13 @@ config SND_DEBUG_DETECT
 	help
 	  Say Y here to enable extra-verbose log messages printed when
 	  detecting devices.
+
+config SND_PCM_XRUN_DEBUG
+	bool "Enable PCM ring buffer overrun/underrun debugging"
+	default n
+	depends on SND_DEBUG
+	help
+	  Say Y to enable the PCM ring buffer overrun/underrun debugging.
+	  It is usually not required, but if you have trouble with
+	  sound clicking when system is loaded, it may help to determine
+	  the process or driver which causes the scheduling gaps.

sound/core/pcm.c

@@ -436,7 +436,7 @@ static void snd_pcm_substream_proc_status_read(struct snd_info_entry *entry,
 	snd_iprintf(buffer, "appl_ptr    : %ld\n", runtime->control->appl_ptr);
 }
 
-#ifdef CONFIG_SND_DEBUG
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
 static void snd_pcm_xrun_debug_read(struct snd_info_entry *entry,
 				    struct snd_info_buffer *buffer)
 {
@@ -480,7 +480,7 @@ static int snd_pcm_stream_proc_init(struct snd_pcm_str *pstr)
 	}
 	pstr->proc_info_entry = entry;
 
-#ifdef CONFIG_SND_DEBUG
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
 	if ((entry = snd_info_create_card_entry(pcm->card, "xrun_debug",
 						pstr->proc_root)) != NULL) {
 		entry->c.text.read_size = 64;
@@ -501,7 +501,7 @@ static int snd_pcm_stream_proc_init(struct snd_pcm_str *pstr)
 
 static int snd_pcm_stream_proc_done(struct snd_pcm_str *pstr)
 {
-#ifdef CONFIG_SND_DEBUG
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
 	if (pstr->proc_xrun_debug_entry) {
 		snd_info_unregister(pstr->proc_xrun_debug_entry);
 		pstr->proc_xrun_debug_entry = NULL;

sound/core/pcm_lib.c

@@ -130,7 +130,7 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram
 static void xrun(struct snd_pcm_substream *substream)
 {
 	snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
-#ifdef CONFIG_SND_DEBUG
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
 	if (substream->pstr->xrun_debug) {
 		snd_printd(KERN_DEBUG "XRUN: pcmC%dD%d%c\n",
 			   substream->pcm->card->number,
@@ -204,7 +204,7 @@ static inline int snd_pcm_update_hw_ptr_interrupt(struct snd_pcm_substream *subs
 	delta = hw_ptr_interrupt - new_hw_ptr;
 	if (delta > 0) {
 		if ((snd_pcm_uframes_t)delta < runtime->buffer_size / 2) {
-#ifdef CONFIG_SND_DEBUG
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
 			if (runtime->periods > 1 && substream->pstr->xrun_debug) {
 				snd_printd(KERN_ERR "Unexpected hw_pointer value [1] (stream = %i, delta: -%ld, max jitter = %ld): wrong interrupt acknowledge?\n", substream->stream, (long) delta, runtime->buffer_size / 2);
 				if (substream->pstr->xrun_debug > 1)
@@ -249,7 +249,7 @@ int snd_pcm_update_hw_ptr(struct snd_pcm_substream *substream)
 	delta = old_hw_ptr - new_hw_ptr;
 	if (delta > 0) {
 		if ((snd_pcm_uframes_t)delta < runtime->buffer_size / 2) {
-#ifdef CONFIG_SND_DEBUG
+#ifdef CONFIG_SND_PCM_XRUN_DEBUG
 			if (runtime->periods > 2 && substream->pstr->xrun_debug) {
 				snd_printd(KERN_ERR "Unexpected hw_pointer value [2] (stream = %i, delta: -%ld, max jitter = %ld): wrong interrupt acknowledge?\n", substream->stream, (long) delta, runtime->buffer_size / 2);
 				if (substream->pstr->xrun_debug > 1)