ALSA: pcm: tracepoints for refining PCM parameters

When working for devices which support configurable modes for its data
transmission or which consists of several components, developers are
likely to use rules of parameters of PCM substream. However, there's no
infrastructure to assist their work.

In old days, ALSA PCM core got a local 'RULES_DEBUG' macro to debug
refinement of parameters for PCM substream. Although this is merely a
makeshift. With some modifications, we get the infrastructure.

This commit is for the purpose. Refinement of mask/interval type of
PCM parameters is probed as tracepoint events as 'hw_mask_param' and
'hw_interval_param' on existent 'snd_pcm' subsystem.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/Makefile

@@ -22,6 +22,7 @@ snd-pcm-$(CONFIG_SND_PCM_IEC958) += pcm_iec958.o
 
 # for trace-points
 CFLAGS_pcm_lib.o := -I$(src)
+CFLAGS_pcm_native.o := -I$(src)
 
 snd-pcm-dmaengine-objs := pcm_dmaengine.o
 

sound/core/pcm_native.c

@@ -39,6 +39,9 @@
 
 #include "pcm_local.h"
 
+#define CREATE_TRACE_POINTS
+#include "pcm_param_trace.h"
+
 /*
  *  Compatibility
  */
@@ -279,6 +282,9 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 	unsigned int stamp = 2;
 	int changed, again;
 
+	struct snd_mask __maybe_unused old_mask;
+	struct snd_interval __maybe_unused old_interval;
+
 	params->info = 0;
 	params->fifo_size = 0;
 	if (params->rmask & (1 << SNDRV_PCM_HW_PARAM_SAMPLE_BITS))
@@ -294,6 +300,9 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 			return -EINVAL;
 		if (!(params->rmask & (1 << k)))
 			continue;
+
+		if (trace_hw_mask_param_enabled())
+			old_mask = *m;
 #ifdef RULES_DEBUG
 		pr_debug("%s = ", snd_pcm_hw_param_names[k]);
 		pr_cont("%04x%04x%04x%04x -> ", m->bits[3], m->bits[2], m->bits[1], m->bits[0]);
@@ -302,6 +311,8 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 #ifdef RULES_DEBUG
 		pr_cont("%04x%04x%04x%04x\n", m->bits[3], m->bits[2], m->bits[1], m->bits[0]);
 #endif
+		trace_hw_mask_param(substream, k, 0, &old_mask, m);
+
 		if (changed)
 			params->cmask |= 1 << k;
 		if (changed < 0)
@@ -314,6 +325,9 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 			return -EINVAL;
 		if (!(params->rmask & (1 << k)))
 			continue;
+
+		if (trace_hw_interval_param_enabled())
+			old_interval = *i;
 #ifdef RULES_DEBUG
 		pr_debug("%s = ", snd_pcm_hw_param_names[k]);
 		if (i->empty)
@@ -333,6 +347,8 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 			       i->openmin ? '(' : '[', i->min,
 			       i->max, i->openmax ? ')' : ']');
 #endif
+		trace_hw_interval_param(substream, k, 0, &old_interval, i);
+
 		if (changed)
 			params->cmask |= 1 << k;
 		if (changed < 0)
@@ -359,6 +375,15 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 			}
 			if (!doit)
 				continue;
+
+			if (trace_hw_mask_param_enabled()) {
+				if (hw_is_mask(r->var))
+					old_mask = *hw_param_mask(params, r->var);
+			}
+			if (trace_hw_interval_param_enabled()) {
+				if (hw_is_interval(r->var))
+					old_interval = *hw_param_interval(params, r->var);
+			}
 #ifdef RULES_DEBUG
 			pr_debug("Rule %d [%p]: ", k, r->func);
 			if (r->var >= 0) {
@@ -394,6 +419,14 @@ int snd_pcm_hw_refine(struct snd_pcm_substream *substream,
 			}
 			pr_cont("\n");
 #endif
+			if (hw_is_mask(r->var)) {
+				trace_hw_mask_param(substream, r->var, k + 1,
+					&old_mask, hw_param_mask(params, r->var));
+			}
+			if (hw_is_interval(r->var)) {
+				trace_hw_interval_param(substream, r->var, k + 1,
+					&old_interval, hw_param_interval(params, r->var));
+			}
 			rstamps[k] = stamp;
 			if (changed && r->var >= 0) {
 				params->cmask |= (1 << r->var);

sound/core/pcm_param_trace.h

@@ -0,0 +1,142 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM snd_pcm
+
+#if !defined(_PCM_PARAMS_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _PCM_PARAMS_TRACE_H
+
+#include <linux/tracepoint.h>
+
+#define HW_PARAM_ENTRY(param) {SNDRV_PCM_HW_PARAM_##param, #param}
+#define hw_param_labels			\
+	HW_PARAM_ENTRY(ACCESS),		\
+	HW_PARAM_ENTRY(FORMAT),		\
+	HW_PARAM_ENTRY(SUBFORMAT),	\
+	HW_PARAM_ENTRY(SAMPLE_BITS),	\
+	HW_PARAM_ENTRY(FRAME_BITS),	\
+	HW_PARAM_ENTRY(CHANNELS),	\
+	HW_PARAM_ENTRY(RATE),		\
+	HW_PARAM_ENTRY(PERIOD_TIME),	\
+	HW_PARAM_ENTRY(PERIOD_SIZE),	\
+	HW_PARAM_ENTRY(PERIOD_BYTES),	\
+	HW_PARAM_ENTRY(PERIODS),	\
+	HW_PARAM_ENTRY(BUFFER_TIME),	\
+	HW_PARAM_ENTRY(BUFFER_SIZE),	\
+	HW_PARAM_ENTRY(BUFFER_BYTES),	\
+	HW_PARAM_ENTRY(TICK_TIME)
+
+TRACE_EVENT(hw_mask_param,
+	TP_PROTO(struct snd_pcm_substream *substream, snd_pcm_hw_param_t type, int index, const struct snd_mask *prev, const struct snd_mask *curr),
+	TP_ARGS(substream, type, index, prev, curr),
+	TP_STRUCT__entry(
+		__field(int, card)
+		__field(int, device)
+		__field(int, subdevice)
+		__field(int, direction)
+		__field(snd_pcm_hw_param_t, type)
+		__field(int, index)
+		__field(int, total)
+		__array(__u32, prev_bits, 8)
+		__array(__u32, curr_bits, 8)
+	),
+	TP_fast_assign(
+		__entry->card = substream->pcm->card->number;
+		__entry->device = substream->pcm->device;
+		__entry->subdevice = substream->number;
+		__entry->direction = substream->stream;
+		__entry->type = type;
+		__entry->index = index;
+		__entry->total = substream->runtime->hw_constraints.rules_num;
+		memcpy(__entry->prev_bits, prev->bits, sizeof(__u32) * 8);
+		memcpy(__entry->curr_bits, curr->bits, sizeof(__u32) * 8);
+	),
+	TP_printk("%d,%d,%d,%d %03d/%03d %s %08x%08x%08x%08x %08x%08x%08x%08x",
+		  __entry->card,
+		  __entry->device,
+		  __entry->subdevice,
+		  __entry->direction,
+		  __entry->index,
+		  __entry->total,
+		  __print_symbolic(__entry->type, hw_param_labels),
+		  __entry->prev_bits[3], __entry->prev_bits[2],
+		  __entry->prev_bits[1], __entry->prev_bits[0],
+		  __entry->curr_bits[3], __entry->curr_bits[2],
+		  __entry->curr_bits[1], __entry->curr_bits[0]
+	)
+);
+
+TRACE_EVENT(hw_interval_param,
+	TP_PROTO(struct snd_pcm_substream *substream, snd_pcm_hw_param_t type, int index, const struct snd_interval *prev, const struct snd_interval *curr),
+	TP_ARGS(substream, type, index, prev, curr),
+	TP_STRUCT__entry(
+		__field(int, card)
+		__field(int, device)
+		__field(int, subdevice)
+		__field(int, direction)
+		__field(snd_pcm_hw_param_t, type)
+		__field(int, index)
+		__field(int, total)
+		__field(unsigned int, prev_min)
+		__field(unsigned int, prev_max)
+		__field(unsigned int, prev_openmin)
+		__field(unsigned int, prev_openmax)
+		__field(unsigned int, prev_integer)
+		__field(unsigned int, prev_empty)
+		__field(unsigned int, curr_min)
+		__field(unsigned int, curr_max)
+		__field(unsigned int, curr_openmin)
+		__field(unsigned int, curr_openmax)
+		__field(unsigned int, curr_integer)
+		__field(unsigned int, curr_empty)
+	),
+	TP_fast_assign(
+		__entry->card = substream->pcm->card->number;
+		__entry->device = substream->pcm->device;
+		__entry->subdevice = substream->number;
+		__entry->direction = substream->stream;
+		__entry->type = type;
+		__entry->index = index;
+		__entry->total = substream->runtime->hw_constraints.rules_num;
+		__entry->prev_min = prev->min;
+		__entry->prev_max = prev->max;
+		__entry->prev_openmin = prev->openmin;
+		__entry->prev_openmax = prev->openmax;
+		__entry->prev_integer = prev->integer;
+		__entry->prev_empty = prev->empty;
+		__entry->curr_min = curr->min;
+		__entry->curr_max = curr->max;
+		__entry->curr_openmin = curr->openmin;
+		__entry->curr_openmax = curr->openmax;
+		__entry->curr_integer = curr->integer;
+		__entry->curr_empty = curr->empty;
+	),
+	TP_printk("%d,%d,%d,%d %03d/%03d %s %d %d %s%u %u%s %d %d %s%u %u%s",
+		  __entry->card,
+		  __entry->device,
+		  __entry->subdevice,
+		  __entry->direction,
+		  __entry->index,
+		  __entry->total,
+		  __print_symbolic(__entry->type, hw_param_labels),
+		  __entry->prev_empty,
+		  __entry->prev_integer,
+		  __entry->prev_openmin ? "(" : "[",
+		  __entry->prev_min,
+		  __entry->prev_max,
+		  __entry->prev_openmax ? ")" : "]",
+		  __entry->curr_empty,
+		  __entry->curr_integer,
+		  __entry->curr_openmin ? "(" : "[",
+		  __entry->curr_min,
+		  __entry->curr_max,
+		  __entry->curr_openmax ? ")" : "]"
+	)
+);
+
+#endif /* _PCM_PARAMS_TRACE_H */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE pcm_param_trace
+#include <trace/define_trace.h>