Parameters: Add support for volatile parameters

Volatile parameters are ones that do not represent a fundamental configuration change but rather than incrementally changing settings. These include logged flight hours or sensor offsets. Marking them as volatile avoids these parameters forcing time-consuming telemetry updates.

src/modules/systemlib/param/param.c

@@ -1,6 +1,6 @@
 /****************************************************************************
  *
- *   Copyright (c) 2012-2015 PX4 Development Team. All rights reserved.
+ *   Copyright (c) 2012-2018 PX4 Development Team. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -489,6 +489,12 @@ param_name(param_t param)
 	return handle_in_range(param) ? param_info_base[param].name : NULL;
 }
 
+bool
+param_is_volatile(param_t param)
+{
+	return handle_in_range(param) ? param_info_base[param].volatile_param : false;
+}
+
 bool
 param_value_is_default(param_t param)
 {
@@ -510,8 +516,9 @@ param_value_unsaved(param_t param)
 	return ret;
 }
 
-enum param_type_e
-param_type(param_t param) {
+param_type_t
+param_type(param_t param)
+{
 	return handle_in_range(param) ? param_info_base[param].type : PARAM_TYPE_UNKNOWN;
 }
 
@@ -680,7 +687,6 @@ param_control_autosave(bool enable)
 #endif /* PARAM_NO_AUTOSAVE */
 }
 
-
 static int
 param_set_internal(param_t param, const void *val, bool mark_saved, bool notify_changes)
 {
@@ -1357,7 +1363,7 @@ uint32_t param_hash_check(void)
 
 	/* compute the CRC32 over all string param names and 4 byte values */
 	for (param_t param = 0; handle_in_range(param); param++) {
-		if (!param_used(param)) {
+		if (!param_used(param) && param_is_volatile(param)) {
 			continue;
 		}
 

src/modules/systemlib/param/param.h

@@ -50,24 +50,20 @@
 #include <sys/types.h>
 
 /** Maximum size of the parameter backing file */
-#define PARAM_FILE_MAXSIZE	4096
+#define PARAM_FILE_MAXSIZE		4096
 
 __BEGIN_DECLS
 
 /**
  * Parameter types.
  */
-typedef enum param_type_e {
-	/* globally-known parameter types */
-	PARAM_TYPE_INT32 = 0,
-	PARAM_TYPE_FLOAT,
+#define PARAM_TYPE_INT32		0
+#define PARAM_TYPE_FLOAT		1
+#define PARAM_TYPE_STRUCT		100
+#define PARAM_TYPE_STRUCT_MAX	(16384 + PARAM_TYPE_STRUCT)
+#define PARAM_TYPE_UNKNOWN		(0xffff)
 
-	/* structure parameters; size is encoded in the type value */
-	PARAM_TYPE_STRUCT = 100,
-	PARAM_TYPE_STRUCT_MAX = 16384 + PARAM_TYPE_STRUCT,
-
-	PARAM_TYPE_UNKNOWN = 0xffff
-} param_type_t;
+typedef uint16_t param_type_t;
 
 
 #ifdef __PX4_NUTTX // on NuttX use 16 bits to save RAM
@@ -198,6 +194,14 @@ __EXPORT int		param_get_used_index(param_t param);
  */
 __EXPORT const char	*param_name(param_t param);
 
+/**
+ * Obtain the volatile state of a parameter.
+ *
+ * @param param		A handle returned by param_find or passed by param_foreach.
+ * @return			true if the parameter is volatile
+ */
+__EXPORT bool		param_is_volatile(param_t param);
+
 /**
  * Test whether a parameter's value has changed from the default.
  *
@@ -262,7 +266,7 @@ __EXPORT int		param_set_no_notification(param_t param, const void *val);
  * Notify the system about parameter changes. Can be used for example after several calls to
  * param_set_no_notification() to avoid unnecessary system notifications.
  */
-__EXPORT void param_notify_changes(void);
+__EXPORT void		param_notify_changes(void);
 
 /**
  * Reset a parameter to its default value.
@@ -282,7 +286,6 @@ __EXPORT int		param_reset(param_t param);
  */
 __EXPORT void		param_reset_all(void);
 
-
 /**
  * Reset all parameters to their default values except for excluded parameters.
  *
@@ -446,6 +449,7 @@ struct param_info_s {
 	;
 #endif
 	param_type_t	type;
+	uint16_t		volatile_param: 1;
 	union param_value_u val;
 };
 

src/modules/systemlib/param/templates/px4_parameters.c.jinja

@@ -16,6 +16,11 @@ struct px4_parameters_t px4_parameters = {
 	{
 		"{{ param.attrib["name"] }}",
 		PARAM_TYPE_{{ param.attrib["type"] }},
+	{%- if param.attrib["volatile"] == "true" %}
+		.volatile_param = 1,
+	{%- else %}
+		.volatile_param = 0,
+	{%- endif %}
 	{%- if param.attrib["type"] == "FLOAT" %}
 		.val.f = {{ param.attrib["default"] }}
 	{%- elif param.attrib["type"] == "INT32" %}