ASoC: dapm: Consolidate input and output path handling

After the recent cleanups and generalizations of the DAPM algorithm the
handling of input and output paths is now fully symmetric. This means by
making some slight changes to the data structure and using arrays with one
entry for each direction, rather than separate fields, it is possible to
create a generic implementation that is capable of handling both input and
output paths.

Unfortunately this generalization significantly increases the code size on
the hot path of is_connected_{input,output}_ep() and
dapm_widget_invalidate_{input,output}_paths(), which has a negative impact
on the overall performance. The inner loops of those functions are quite
small and the generic implementation adds extra pointer arithmetic in a few
places.

Testing on ARM shows that the combined code size of the specialized
functions is about 50% larger than the generalized function in relative
numbers. But in absolute numbers its less than 200 bytes, which is still
quite small. On the other hand the generalized function increases the
execution time of dapm_power_one_widget() by 30%. Given that this function
is one of the most often called functions of the DAPM framework the
trade-off of getting better performance at expense of generating slightly
larger code at seems to be worth it.

To avoid this still keep two versions of these functions around, one for
input and one for output. But have a generic implementation of the
algorithm which gets inlined by those two versions. And then let the
compiler take care of optimizing it and removing he extra instructions.

This still reduces the source code size as well as the makes making changes
to the implementation more straight forward since the same change does no
longer need to be done in two separate places. Also on the slow paths we
can use a generic implementations that handle both input and output paths.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-dapm.h

@@ -512,9 +512,18 @@ struct snd_soc_dapm_route {
 struct snd_soc_dapm_path {
 	const char *name;
 
-	/* source (input) and sink (output) widgets */
+	/*
+	 * source (input) and sink (output) widgets
+	 * The union is for convience, since it is a lot nicer to type
+	 * p->source, rather than p->node[SND_SOC_DAPM_DIR_IN]
+	 */
+	union {
+		struct {
 			struct snd_soc_dapm_widget *source;
 			struct snd_soc_dapm_widget *sink;
+		};
+		struct snd_soc_dapm_widget *node[2];
+	};
 
 	/* status */
 	u32 connect:1;	/* source and sink widgets are connected */
@@ -525,8 +534,7 @@ struct snd_soc_dapm_path {
 	int (*connected)(struct snd_soc_dapm_widget *source,
 			 struct snd_soc_dapm_widget *sink);
 
-	struct list_head list_source;
-	struct list_head list_sink;
+	struct list_head list_node[2];
 	struct list_head list_kcontrol;
 	struct list_head list;
 };
@@ -560,8 +568,7 @@ struct snd_soc_dapm_widget {
 	unsigned char new_power:1;		/* power from this run */
 	unsigned char power_checked:1;		/* power checked this run */
 	unsigned char is_supply:1;		/* Widget is a supply type widget */
-	unsigned char is_sink:1;		/* Widget is a sink type widget */
-	unsigned char is_source:1;		/* Widget is a source type widget */
+	unsigned char is_ep:2;			/* Widget is a endpoint type widget */
 	int subseq;				/* sort within widget type */
 
 	int (*power_check)(struct snd_soc_dapm_widget *w);
@@ -576,16 +583,14 @@ struct snd_soc_dapm_widget {
 	struct snd_kcontrol **kcontrols;
 	struct snd_soc_dobj dobj;
 
-	/* widget input and outputs */
-	struct list_head sources;
-	struct list_head sinks;
+	/* widget input and output edges */
+	struct list_head edges[2];
 
 	/* used during DAPM updates */
 	struct list_head work_list;
 	struct list_head power_list;
 	struct list_head dirty;
-	int inputs;
-	int outputs;
+	int endpoints[2];
 
 	struct clk *clk;
 };
@@ -673,6 +678,42 @@ static inline enum snd_soc_bias_level snd_soc_dapm_get_bias_level(
 	return dapm->bias_level;
 }
 
+enum snd_soc_dapm_direction {
+	SND_SOC_DAPM_DIR_IN,
+	SND_SOC_DAPM_DIR_OUT
+};
+
+#define SND_SOC_DAPM_DIR_TO_EP(x) BIT(x)
+
+#define SND_SOC_DAPM_EP_SOURCE SND_SOC_DAPM_DIR_TO_EP(SND_SOC_DAPM_DIR_IN)
+#define SND_SOC_DAPM_EP_SINK SND_SOC_DAPM_DIR_TO_EP(SND_SOC_DAPM_DIR_OUT)
+
+/**
+ * snd_soc_dapm_widget_for_each_sink_path - Iterates over all paths in the
+ *   specified direction of a widget
+ * @w: The widget
+ * @dir: Whether to iterate over the paths where the specified widget is the
+ *       incoming or outgoing widgets
+ * @p: The path iterator variable
+ */
+#define snd_soc_dapm_widget_for_each_path(w, dir, p) \
+	list_for_each_entry(p, &w->edges[dir], list_node[dir])
+
+/**
+ * snd_soc_dapm_widget_for_each_sink_path_safe - Iterates over all paths in the
+ *   specified direction of a widget
+ * @w: The widget
+ * @dir: Whether to iterate over the paths where the specified widget is the
+ *       incoming or outgoing widgets
+ * @p: The path iterator variable
+ * @next_p: Temporary storage for the next path
+ *
+ *  This function works like snd_soc_dapm_widget_for_each_sink_path, expect that
+ *  it is safe to remove the current path from the list while iterating
+ */
+#define snd_soc_dapm_widget_for_each_path_safe(w, dir, p, next_p) \
+	list_for_each_entry_safe(p, next_p, &w->edges[dir], list_node[dir])
+
 /**
  * snd_soc_dapm_widget_for_each_sink_path - Iterates over all paths leaving a
  *  widget
@@ -680,7 +721,7 @@ static inline enum snd_soc_bias_level snd_soc_dapm_get_bias_level(
  * @p: The path iterator variable
  */
 #define snd_soc_dapm_widget_for_each_sink_path(w, p) \
-	list_for_each_entry(p, &w->sinks, list_source)
+	snd_soc_dapm_widget_for_each_path(w, SND_SOC_DAPM_DIR_IN, p)
 
 /**
  * snd_soc_dapm_widget_for_each_source_path - Iterates over all paths leading to
@@ -689,6 +730,6 @@ static inline enum snd_soc_bias_level snd_soc_dapm_get_bias_level(
  * @p: The path iterator variable
  */
 #define snd_soc_dapm_widget_for_each_source_path(w, p) \
-	list_for_each_entry(p, &w->sources, list_sink)
+	snd_soc_dapm_widget_for_each_path(w, SND_SOC_DAPM_DIR_OUT, p)
 
 #endif