hwdriver: Introduce sr_config_commit() API call.

(sr_dev_driver.config_probe_set): New optional callback enabling
drivers to be notified upon changes to probe settings.
(sr_dev_probe_enable, sr_dev_trigger_set): Invoke new driver
callback on changes.
(sr_dev_driver.config_commit): New optional callback allowing
drivers to defer application of configuration settings until
an explicit call to config_commit().
(sr_config_commit): New public wrapper function.

device.c

@@ -116,7 +116,9 @@ SR_API int sr_dev_probe_name_set(const struct sr_dev_inst *sdi,
  * @param probenum The probe number, starting from 0.
  * @param state TRUE to enable the probe, FALSE to disable.
  *
- * @return SR_OK on success, or SR_ERR_ARG on invalid arguments.
+ * @return SR_OK on success or SR_ERR on failure.  In case of invalid
+ *         arguments, SR_ERR_ARG is returned and the probe enabled state
+ *         remains unchanged.
  *
  * @since 0.2.0
  */
@@ -126,6 +128,7 @@ SR_API int sr_dev_probe_enable(const struct sr_dev_inst *sdi, int probenum,
 	GSList *l;
 	struct sr_probe *probe;
 	int ret;
+	gboolean was_enabled;
 
 	if (!sdi)
 		return SR_ERR_ARG;
@@ -134,8 +137,17 @@ SR_API int sr_dev_probe_enable(const struct sr_dev_inst *sdi, int probenum,
 	for (l = sdi->probes; l; l = l->next) {
 		probe = l->data;
 		if (probe->index == probenum) {
+			was_enabled = probe->enabled;
 			probe->enabled = state;
 			ret = SR_OK;
+			if (!state != !was_enabled && sdi->driver
+					&& sdi->driver->config_probe_set) {
+				ret = sdi->driver->config_probe_set(
+					sdi, probe, SR_PROBE_SET_ENABLED);
+				/* Roll back change if it wasn't applicable. */
+				if (ret == SR_ERR_ARG)
+					probe->enabled = was_enabled;
+			}
 			break;
 		}
 	}
@@ -153,7 +165,9 @@ SR_API int sr_dev_probe_enable(const struct sr_dev_inst *sdi, int probenum,
  * @param[in] probenum Number of probe, starting at 0.
  * @param[in] trigger Trigger string, in the format used by sigrok-cli
  *
- * @return SR_OK on success, or SR_ERR_ARG on invalid arguments.
+ * @return SR_OK on success or SR_ERR on failure.  In case of invalid
+ *         arguments, SR_ERR_ARG is returned and the trigger settings
+ *         remain unchanged.
  *
  * @since 0.2.0
  */
@@ -162,6 +176,7 @@ SR_API int sr_dev_trigger_set(const struct sr_dev_inst *sdi, int probenum,
 {
 	GSList *l;
 	struct sr_probe *probe;
+	char *old_trigger;
 	int ret;
 
 	if (!sdi)
@@ -171,10 +186,24 @@ SR_API int sr_dev_trigger_set(const struct sr_dev_inst *sdi, int probenum,
 	for (l = sdi->probes; l; l = l->next) {
 		probe = l->data;
 		if (probe->index == probenum) {
-			/* If the probe already has a trigger, kill it first. */
-			g_free(probe->trigger);
-			probe->trigger = g_strdup(trigger);
+			old_trigger = probe->trigger;
 			ret = SR_OK;
+			if (g_strcmp0(trigger, old_trigger) == 0)
+				break;
+			/* Set new trigger if it has changed. */
+			probe->trigger = g_strdup(trigger);
+
+			if (sdi->driver && sdi->driver->config_probe_set) {
+				ret = sdi->driver->config_probe_set(
+					sdi, probe, SR_PROBE_SET_TRIGGER);
+				/* Roll back change if it wasn't applicable. */
+				if (ret == SR_ERR_ARG) {
+					g_free(probe->trigger);
+					probe->trigger = old_trigger;
+					break;
+				}
+			}
+			g_free(old_trigger);
 			break;
 		}
 	}

hwdriver.c

@@ -633,6 +633,27 @@ SR_API int sr_config_set(const struct sr_dev_inst *sdi,
 	return ret;
 }
 
+/**
+ * Apply configuration settings to the device hardware.
+ *
+ * @param sdi The device instance.
+ *
+ * @return SR_OK upon success or SR_ERR in case of error.
+ */
+SR_API int sr_config_commit(const struct sr_dev_inst *sdi)
+{
+	int ret;
+
+	if (!sdi || !sdi->driver)
+		ret = SR_ERR;
+	else if (!sdi->driver->config_commit)
+		ret = SR_OK;
+	else
+		ret = sdi->driver->config_commit(sdi);
+
+	return ret;
+}
+
 /**
  * List all possible values for a configuration key.
  *

libsigrok-internal.h

@@ -174,6 +174,14 @@ SR_PRIV int sr_err(const char *format, ...);
 
 /*--- device.c --------------------------------------------------------------*/
 
+/** Values for the changes argument of sr_dev_driver.config_probe_set. */
+enum {
+	/** The enabled state of the probe has been changed. */
+	SR_PROBE_SET_ENABLED = 1 << 0,
+	/** The trigger setup of the probe has been changed. */
+	SR_PROBE_SET_TRIGGER = 1 << 1,
+};
+
 SR_PRIV struct sr_probe *sr_probe_new(int index, int type,
 		gboolean enabled, const char *name);
 

libsigrok.h

@@ -975,6 +975,9 @@ struct sr_dev_driver {
 	int (*config_set) (int id, GVariant *data,
 			const struct sr_dev_inst *sdi,
 			const struct sr_probe_group *probe_group);
+	int (*config_probe_set) (const struct sr_dev_inst *sdi,
+			struct sr_probe *probe, unsigned int changes);
+	int (*config_commit) (const struct sr_dev_inst *sdi);
 	int (*config_list) (int info_id, GVariant **data,
 			const struct sr_dev_inst *sdi,
 			const struct sr_probe_group *probe_group);

proto.h

@@ -77,6 +77,7 @@ SR_API int sr_config_get(const struct sr_dev_driver *driver,
 SR_API int sr_config_set(const struct sr_dev_inst *sdi,
 		const struct sr_probe_group *probe_group,
 		int key, GVariant *data);
+SR_API int sr_config_commit(const struct sr_dev_inst *sdi);
 SR_API int sr_config_list(const struct sr_dev_driver *driver,
 		const struct sr_dev_inst *sdi,
 		const struct sr_probe_group *probe_group,