Rework hardware probing and RTL-SDR helper startup

The lazy startup of the separate helper program for the RTL-SDR
backend on playback start was incorrect with respect to the expected
behavior the frequency setting verbs.  This was not visible during
usage by the radio application, but was triggering failures in
several tests in the pyagl binding wrapper test suite.  To facilitate
starting the helper during backend initialization, the probing part
of the backend "init" has been split into a separate "probe" function,
and all backends have been updated to reflect this change.  Logic has
been added to enforce that "init" is only called after "probe" has
succeeded for a backend, and a comment has been added to radio_impl.h
to document this intended behavior.

Bug-AGL: SPEC-3717

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: Ic37331a92bae7cc01ee448e69894fa5f49d08a74

1 files changed, 32 insertions, 17 deletions

diff --git a/binding/radio_impl_kingfisher.c b/binding/radio_impl_kingfisher.c
index dc59916..b7d243b 100644
--- a/binding/radio_impl_kingfisher.c
+++ b/binding/radio_impl_kingfisher.c
@@ -57,12 +57,13 @@ static fm_band_plan_t known_fm_band_plans[5] = {
 };
 
 static unsigned int bandplan = 0;
-static bool corking = false;
-static bool present = false;
+static bool corking;
+static bool present;
+static bool initialized;
 static uint32_t current_frequency;
 static int scan_valid_snr_threshold = 128;
 static int scan_valid_rssi_threshold = 128;
-static bool scanning = false;
+static bool scanning;
 
 // stream state
 static GstElement *pipeline;
@@ -104,16 +105,9 @@ static void *gstreamer_loop_thread(void *ptr)
 	return NULL;
 }
 
-static int kf_init(void)
+static int kf_probe(void)
 {
-	GKeyFile* conf_file;
-	int conf_file_present = 0;
 	struct stat statbuf;
-	char *value_str;
-	char cmd[SI_CTL_CMDLINE_MAXLEN];
-	int rc;
-	char gst_pipeline_str[GST_PIPELINE_LEN];
-	pthread_t thread_id;
 
 	if(present)
 		return 0;
@@ -126,6 +120,26 @@ static int kf_init(void)
 	if(stat(SI_CTL, &statbuf) != 0)
 		return -1;
 
+	present = true;
+	return 0;
+}
+
+static int kf_init(void)
+{
+	GKeyFile* conf_file;
+	bool conf_file_present = false;
+	char *value_str;
+	char cmd[SI_CTL_CMDLINE_MAXLEN];
+	int rc;
+	char gst_pipeline_str[GST_PIPELINE_LEN];
+	pthread_t thread_id;
+
+	if(!present)
+		return -1;
+
+	if(initialized)
+		return 0;
+
 	// Load settings from configuration file if it exists
 	conf_file = g_key_file_new();
 	if(conf_file &&
@@ -135,7 +149,7 @@ static int kf_init(void)
 				     NULL,
 				     G_KEY_FILE_KEEP_COMMENTS,
 				     NULL) == TRUE) {
-		conf_file_present = 1;
+		conf_file_present = true;
 
 		// Set band plan if it is specified
 		value_str = g_key_file_get_string(conf_file,
@@ -229,7 +243,7 @@ static int kf_init(void)
 	if(rc != 0)
 		return rc;
 
-	present = true;
+	initialized = true;
 	return 0;
 }
 
@@ -247,7 +261,7 @@ static void kf_set_frequency(uint32_t frequency)
 	char cmd[SI_CTL_CMDLINE_MAXLEN];
 	int rc;
 
-	if(!present)
+	if(!initialized)
 		return;
 
 	if(scanning)
@@ -363,7 +377,7 @@ static bool kf_get_corking_state(void)
 
 static void kf_start(void)
 {
-	if(!present)
+	if(!initialized)
 		return;
 
 	if(!running || corking) {
@@ -378,7 +392,7 @@ static void kf_stop(void)
 {
 	GstEvent *event;
 
-	if(present && running) {
+	if(initialized && running) {
 		// Stop pipeline
 		running = false;
 
@@ -416,7 +430,7 @@ static void kf_scan_start(radio_scan_direction_t direction,
 	uint32_t new_frequency = 0;
 	FILE *fp;
 
-	if(!present)
+	if(!initialized)
 		return;
 
 	if(scanning)
@@ -487,6 +501,7 @@ static void kf_set_stereo_mode(radio_stereo_mode_t mode)
 
 radio_impl_ops_t kf_impl_ops = {
 	.name = "Kingfisher Si4689",
+	.probe = kf_probe,
 	.init = kf_init,
 	.set_output = kf_set_output,
 	.get_frequency = kf_get_frequency,