X-Git-Url: https://sigrok.org/gitweb/?a=blobdiff_plain;f=src%2Fhardware%2Fhp-3457a%2Fapi.c;fp=src%2Fhardware%2Fhp-3457a%2Fapi.c;h=4cfc2d758b54e79625609d408ef0f506d028a5b7;hb=69498046f64006a11234b0d281a481338f6f329c;hp=f828cfd817f3743c7c764561c8ac8c5737285cff;hpb=7f0463840ab5d6a85daaa76850558d2b71e596cf;p=libsigrok.git

diff --git a/src/hardware/hp-3457a/api.c b/src/hardware/hp-3457a/api.c
index f828cfd8..4cfc2d75 100644
--- a/src/hardware/hp-3457a/api.c
+++ b/src/hardware/hp-3457a/api.c
@@ -127,6 +127,14 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 	struct sr_dev_inst *sdi;
 	struct dev_context *devc;
 
+	/*
+	 * The device cannot get identified by means of SCPI queries.
+	 * Neither shall non-SCPI requests get emitted before reliable
+	 * identification of the device. Assume that we only get here
+	 * when user specs led us to believe it's safe to communicate
+	 * to the expected kind of device.
+	 */
+
 	/*
 	 * This command ensures we receive an EOI after every response, so that
 	 * we don't wait the entire timeout after the response is received.
@@ -170,6 +178,14 @@ static struct sr_dev_inst *probe_device(struct sr_scpi_dev_inst *scpi)
 
 static GSList *scan(struct sr_dev_driver *di, GSList *options)
 {
+	const char *conn;
+
+	/* Only scan for a device when conn= was specified. */
+	conn = NULL;
+	(void)sr_serial_extract_options(options, &conn, NULL);
+	if (!conn)
+		return NULL;
+
 	return sr_scpi_scan(di->context, options, probe_device);
 }