Chamelium port mapping auto-discovery

index b83ff395d44b..966d78dce146 100644
@@ -538,12 +538,10 @@ struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,
 	xmlrpc_value *res;
 	struct chamelium_edid *chamelium_edid;
 	int edid_id;
-	struct edid *edid = (struct edid *) raw_edid;
-	size_t edid_size = sizeof(struct edid) +
-			   edid->extensions_len * sizeof(struct edid_ext);
+	const struct edid *edid = (struct edid *) raw_edid;
 
 	res = chamelium_rpc(chamelium, NULL, "CreateEdid", "(6)",
-			    raw_edid, edid_size);
+			    raw_edid, edid_get_size(edid));
 
 	xmlrpc_read_int(&chamelium->env, res, &edid_id);
 	xmlrpc_DECREF(res);

index e71136f48e14..6cc5e7dd42c4 100644
@@ -274,6 +274,16 @@ void edid_update_checksum(struct edid *edid)
 					  sizeof(struct edid));
 }
 
+/**
+ * edid_get_size: return the size of the EDID block in bytes including EDID
+ * extensions, if any.
+ */
+size_t edid_get_size(const struct edid *edid)
+{
+	return sizeof(struct edid) +
+	       edid->extensions_len * sizeof(struct edid_ext);
+}
+
 /**
  * cea_sad_init_pcm:
  * @channels: the number of supported channels (max. 8)

index 00596ef1a46f..8d8e30ec0554 100644
@@ -297,6 +297,7 @@ struct edid {
 void edid_init(struct edid *edid);
 void edid_init_with_mode(struct edid *edid, drmModeModeInfo *mode);
 void edid_update_checksum(struct edid *edid);
+size_t edid_get_size(const struct edid *edid);
 void detailed_timing_set_mode(struct detailed_timing *dt, drmModeModeInfo *mode,
 			      int width_mm, int height_mm);
 void detailed_timing_set_monitor_range_mode(struct detailed_timing *dt,

index 966d78dce146..4a3f64b3585d 100644
@@ -564,21 +564,22 @@ static void chamelium_destroy_edid(struct chamelium *chamelium, int edid_id)
  * chamelium_port_set_edid:
  * @chamelium: The Chamelium instance to use
  * @port: The port on the Chamelium to set the EDID on
- * @edid: The Chamelium EDID to set
- * #chamelium_new_edid, or 0 to disable the EDID on the port
+ * @edid: The Chamelium EDID to set or NULL to use the default Chamelium EDID
  *
  * Sets a port on the chamelium to use the specified EDID. This does not fire a
  * hotplug pulse on it's own, and merely changes what EDID the chamelium port
  * will report to us the next time we probe it. Users will need to reprobe the
  * connectors themselves if they want to see the EDID reported by the port
  * change.
+ *
+ * To create an EDID, see #chamelium_new_edid.
  */
 void chamelium_port_set_edid(struct chamelium *chamelium,
 			     struct chamelium_port *port,
 			     struct chamelium_edid *edid)
 {
 	xmlrpc_DECREF(chamelium_rpc(chamelium, NULL, "ApplyEdid", "(ii)",
-				    port->id, edid->id));
+				    port->id, edid ? edid->id : 0));
 }
 
 /**

index 4a3f64b3585d..9ea483eee717 100644
@@ -83,6 +83,7 @@
 
 struct chamelium_edid {
 	int id;
+	struct edid *raw;
 	struct igt_list link;
 };
 

@@ -530,6 +531,11 @@ void chamelium_schedule_hpd_toggle(struct chamelium *chamelium,
  * Uploads and registers a new EDID with the chamelium. The EDID will be
  * destroyed automatically when #chamelium_deinit is called.
  *
+ * Callers shouldn't assume that the raw EDID they provide is uploaded as-is to
+ * the Chamelium. The EDID may be mutated (e.g. a serial number can be appended
+ * to be able to uniquely identify the EDID). To retrieve the exact EDID that
+ * will be applied to a particular port, use #chamelium_edid_get_raw.
+ *
  * Returns: An opaque pointer to the Chamelium EDID
  */
 struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,

@@ -539,16 +545,18 @@ struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,
 	struct chamelium_edid *chamelium_edid;
 	int edid_id;
 	const struct edid *edid = (struct edid *) raw_edid;
+	size_t edid_size = edid_get_size(edid);
 
 	res = chamelium_rpc(chamelium, NULL, "CreateEdid", "(6)",
-			    raw_edid, edid_get_size(edid));
+			    raw_edid, edid_size);
 
 	xmlrpc_read_int(&chamelium->env, res, &edid_id);
 	xmlrpc_DECREF(res);
 
 	chamelium_edid = calloc(1, sizeof(struct chamelium_edid));
 	chamelium_edid->id = edid_id;
-
+	chamelium_edid->raw = malloc(edid_size);
+	memcpy(chamelium_edid->raw, raw_edid, edid_size);
 	igt_list_add(&chamelium_edid->link, &chamelium->edids);
 
 	return chamelium_edid;

@@ -560,6 +568,23 @@ static void chamelium_destroy_edid(struct chamelium *chamelium, int edid_id)
 				    edid_id));
 }
 
+/**
+ * chamelium_edid_get_raw: get the raw EDID
+ * @edid: the Chamelium EDID
+ * @port: the Chamelium port
+ *
+ * The EDID provided to #chamelium_new_edid may be mutated for identification
+ * purposes. This function allows to retrieve the exact EDID that will be set
+ * for a given port.
+ *
+ * The returned raw EDID is only valid until the next call to this function.
+ */
+const struct edid *chamelium_edid_get_raw(struct chamelium_edid *edid,
+					  struct chamelium_port *port)
+{
+	return edid->raw;
+}
+
 /**
  * chamelium_port_set_edid:
  * @chamelium: The Chamelium instance to use

@@ -1898,6 +1923,7 @@ void chamelium_deinit(struct chamelium *chamelium)
 	/* Destroy any EDIDs we created to make sure we don't leak them */
 	igt_list_for_each_safe(pos, tmp, &chamelium->edids, link) {
 		chamelium_destroy_edid(chamelium, pos->id);
+		free(pos->raw);
 		free(pos);
 	}
 

index ce9e9ced75d9..f58e4f1f0c75 100644
@@ -102,6 +102,8 @@ void chamelium_schedule_hpd_toggle(struct chamelium *chamelium,
 				   bool rising_edge);
 struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,
 					  const unsigned char *edid);
+const struct edid *chamelium_edid_get_raw(struct chamelium_edid *edid,
+					  struct chamelium_port *port);
 void chamelium_port_set_edid(struct chamelium *chamelium,
 			     struct chamelium_port *port,
 			     struct chamelium_edid *edid);

index 378024d8fd05..175e5032c973 100644
@@ -276,9 +276,10 @@ static void
 test_edid_read(data_t *data, struct chamelium_port *port, enum test_edid edid)
 {
 	drmModePropertyBlobPtr edid_blob = NULL;
-	const unsigned char *raw_edid = get_edid(edid);
 	drmModeConnector *connector = chamelium_port_get_connector(
 	    data->chamelium, port, false);
+	size_t raw_edid_size;
+	const struct edid *raw_edid;
 	uint64_t edid_blob_id;
 
 	reset_state(data, port);

@@ -295,7 +296,9 @@ test_edid_read(data_t *data, struct chamelium_port *port, enum test_edid edid)
 	igt_assert(edid_blob = drmModeGetPropertyBlob(data->drm_fd,
 						      edid_blob_id));
 
-	igt_assert(memcmp(raw_edid, edid_blob->data, EDID_LENGTH) == 0);
+	raw_edid = chamelium_edid_get_raw(data->edids[edid], port);
+	raw_edid_size = edid_get_size(raw_edid);
+	igt_assert(memcmp(raw_edid, edid_blob->data, raw_edid_size) == 0);
 
 	drmModeFreePropertyBlob(edid_blob);
 	drmModeFreeConnector(connector);

index 9ea483eee717..8e6db445330e 100644
@@ -523,6 +523,26 @@ void chamelium_schedule_hpd_toggle(struct chamelium *chamelium,
 				    "(iii)", port->id, delay_ms, rising_edge));
 }
 
+static int chamelium_upload_edid(struct chamelium *chamelium,
+				 const struct edid *edid)
+{
+	xmlrpc_value *res;
+	int edid_id;
+
+	res = chamelium_rpc(chamelium, NULL, "CreateEdid", "(6)",
+			    edid, edid_get_size(edid));
+	xmlrpc_read_int(&chamelium->env, res, &edid_id);
+	xmlrpc_DECREF(res);
+
+	return edid_id;
+}
+
+static void chamelium_destroy_edid(struct chamelium *chamelium, int edid_id)
+{
+	xmlrpc_DECREF(chamelium_rpc(chamelium, NULL, "DestroyEdid", "(i)",
+				    edid_id));
+}
+
 /**
  * chamelium_new_edid:
  * @chamelium: The Chamelium instance to use

@@ -541,33 +561,22 @@ void chamelium_schedule_hpd_toggle(struct chamelium *chamelium,
 struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,
 					  const unsigned char *raw_edid)
 {
-	xmlrpc_value *res;
 	struct chamelium_edid *chamelium_edid;
 	int edid_id;
 	const struct edid *edid = (struct edid *) raw_edid;
 	size_t edid_size = edid_get_size(edid);
 
-	res = chamelium_rpc(chamelium, NULL, "CreateEdid", "(6)",
-			    raw_edid, edid_size);
-
-	xmlrpc_read_int(&chamelium->env, res, &edid_id);
-	xmlrpc_DECREF(res);
+	edid_id = chamelium_upload_edid(chamelium, edid);
 
 	chamelium_edid = calloc(1, sizeof(struct chamelium_edid));
 	chamelium_edid->id = edid_id;
 	chamelium_edid->raw = malloc(edid_size);
-	memcpy(chamelium_edid->raw, raw_edid, edid_size);
+	memcpy(chamelium_edid->raw, edid, edid_get_size(edid));
 	igt_list_add(&chamelium_edid->link, &chamelium->edids);
 
 	return chamelium_edid;
 }
 
-static void chamelium_destroy_edid(struct chamelium *chamelium, int edid_id)
-{
-	xmlrpc_DECREF(chamelium_rpc(chamelium, NULL, "DestroyEdid", "(i)",
-				    edid_id));
-}
-
 /**
  * chamelium_edid_get_raw: get the raw EDID
  * @edid: the Chamelium EDID

index 8e6db445330e..1b5566f42f44 100644
@@ -120,7 +120,7 @@ struct chamelium {
 	int drm_fd;
 
 	struct igt_list edids;
-	struct chamelium_port *ports;
+	struct chamelium_port ports[CHAMELIUM_MAX_PORTS];
 	int port_count;
 };
 

@@ -1738,11 +1738,9 @@ static bool chamelium_read_port_mappings(struct chamelium *chamelium,
 		if (strstr(group_list[i], "Chamelium:"))
 			chamelium->port_count++;
 	}
+	igt_assert(chamelium->port_count <= CHAMELIUM_MAX_PORTS);
 
-	chamelium->ports = calloc(sizeof(struct chamelium_port),
-				  chamelium->port_count);
 	port_i = 0;
-
 	for (i = 0; group_list[i] != NULL; i++) {
 		group = group_list[i];
 

@@ -1942,7 +1940,6 @@ void chamelium_deinit(struct chamelium *chamelium)
 	for (i = 0; i < chamelium->port_count; i++)
 		free(chamelium->ports[i].name);
 
-	free(chamelium->ports);
 	free(chamelium);
 }
 

index f58e4f1f0c75..c034d72c8910 100644
@@ -61,6 +61,13 @@ struct chamelium_audio_file {
 
 struct chamelium_edid;
 
+/**
+ * CHAMELIUM_MAX_PORTS: the maximum number of ports supported by igt_chamelium.
+ *
+ * For now, we have 1 VGA, 1 HDMI and 2 DisplayPort ports.
+ */
+#define CHAMELIUM_MAX_PORTS 4
+
 /**
  * CHAMELIUM_DEFAULT_EDID: provide this ID to #chamelium_port_set_edid to use
  * the default EDID.

index 1b5566f42f44..467f1a458516 100644
@@ -82,8 +82,8 @@
  */
 
 struct chamelium_edid {
-	int id;
 	struct edid *raw;
+	int ids[CHAMELIUM_MAX_PORTS];
 	struct igt_list link;
 };
 

@@ -562,14 +562,10 @@ struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,
 					  const unsigned char *raw_edid)
 {
 	struct chamelium_edid *chamelium_edid;
-	int edid_id;
 	const struct edid *edid = (struct edid *) raw_edid;
 	size_t edid_size = edid_get_size(edid);
 
-	edid_id = chamelium_upload_edid(chamelium, edid);
-
 	chamelium_edid = calloc(1, sizeof(struct chamelium_edid));
-	chamelium_edid->id = edid_id;
 	chamelium_edid->raw = malloc(edid_size);
 	memcpy(chamelium_edid->raw, edid, edid_get_size(edid));
 	igt_list_add(&chamelium_edid->link, &chamelium->edids);

@@ -612,8 +608,23 @@ void chamelium_port_set_edid(struct chamelium *chamelium,
 			     struct chamelium_port *port,
 			     struct chamelium_edid *edid)
 {
+	int edid_id;
+	size_t port_index;
+	const struct edid *raw_edid;
+
+	if (edid) {
+		port_index = port - chamelium->ports;
+		edid_id = edid->ids[port_index];
+		if (edid_id == 0) {
+			raw_edid = chamelium_edid_get_raw(edid, port);
+			edid_id = chamelium_upload_edid(chamelium, raw_edid);
+		}
+	} else {
+		edid_id = 0;
+	}
+
 	xmlrpc_DECREF(chamelium_rpc(chamelium, NULL, "ApplyEdid", "(ii)",
-				    port->id, edid ? edid->id : 0));
+				    port->id, edid_id));
 }
 
 /**

@@ -1929,7 +1940,10 @@ void chamelium_deinit(struct chamelium *chamelium)
 
 	/* Destroy any EDIDs we created to make sure we don't leak them */
 	igt_list_for_each_safe(pos, tmp, &chamelium->edids, link) {
-		chamelium_destroy_edid(chamelium, pos->id);
+		for (i = 0; i < CHAMELIUM_MAX_PORTS; i++) {
+			if (pos->ids[i])
+				chamelium_destroy_edid(chamelium, pos->ids[i]);
+		}
 		free(pos->raw);
 		free(pos);
 	}

index 467f1a458516..959a14333ed9 100644
@@ -82,7 +82,9 @@
  */
 
 struct chamelium_edid {
-	struct edid *raw;
+	struct chamelium *chamelium;
+	struct edid *base;
+	struct edid *raw[CHAMELIUM_MAX_PORTS];
 	int ids[CHAMELIUM_MAX_PORTS];
 	struct igt_list link;
 };

@@ -566,13 +568,33 @@ struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,
 	size_t edid_size = edid_get_size(edid);
 
 	chamelium_edid = calloc(1, sizeof(struct chamelium_edid));
-	chamelium_edid->raw = malloc(edid_size);
-	memcpy(chamelium_edid->raw, edid, edid_get_size(edid));
+	chamelium_edid->chamelium = chamelium;
+	chamelium_edid->base = malloc(edid_size);
+	memcpy(chamelium_edid->base, edid, edid_get_size(edid));
 	igt_list_add(&chamelium_edid->link, &chamelium->edids);
 
 	return chamelium_edid;
 }
 
+/**
+ * chamelium_port_tag_edid: tag the EDID with the provided Chamelium port.
+ */
+static void chamelium_port_tag_edid(struct chamelium_port *port,
+				    struct edid *edid)
+{
+	uint32_t *serial;
+
+	/* Product code: Chamelium */
+	edid->prod_code[0] = 'C';
+	edid->prod_code[1] = 'H';
+
+	/* Serial: Chamelium port ID */
+	serial = (uint32_t *) &edid->serial;
+	*serial = port->id;
+
+	edid_update_checksum(edid);
+}
+
 /**
  * chamelium_edid_get_raw: get the raw EDID
  * @edid: the Chamelium EDID

@@ -587,7 +609,17 @@ struct chamelium_edid *chamelium_new_edid(struct chamelium *chamelium,
 const struct edid *chamelium_edid_get_raw(struct chamelium_edid *edid,
 					  struct chamelium_port *port)
 {
-	return edid->raw;
+	size_t port_index = port - edid->chamelium->ports;
+	size_t edid_size;
+
+	if (!edid->raw[port_index]) {
+		edid_size = edid_get_size(edid->base);
+		edid->raw[port_index] = malloc(edid_size);
+		memcpy(edid->raw[port_index], edid->base, edid_size);
+		chamelium_port_tag_edid(port, edid->raw[port_index]);
+	}
+
+	return edid->raw[port_index];
 }
 
 /**

@@ -1943,8 +1975,9 @@ void chamelium_deinit(struct chamelium *chamelium)
 		for (i = 0; i < CHAMELIUM_MAX_PORTS; i++) {
 			if (pos->ids[i])
 				chamelium_destroy_edid(chamelium, pos->ids[i]);
+			free(pos->raw[i]);
 		}
-		free(pos->raw);
+		free(pos->base);
 		free(pos);
 	}
 

index 6cc5e7dd42c4..cbb7eefff70d 100644
@@ -172,6 +172,19 @@ void detailed_timing_set_string(struct detailed_timing *dt,
 		ds->str[len] = '\n';
 }
 
+/**
+ * edid_get_mfg: reads the 3-letter manufacturer identifier
+ *
+ * The string is *not* NULL-terminated.
+ */
+void edid_get_mfg(const struct edid *edid, char out[static 3])
+{
+	out[0] = ((edid->mfg_id[0] & 0x7C) >> 2) + '@';
+	out[1] = (((edid->mfg_id[0] & 0x03) << 3) |
+		 ((edid->mfg_id[1] & 0xE0) >> 5)) + '@';
+	out[2] = (edid->mfg_id[1] & 0x1F) + '@';
+}
+
 static void edid_set_mfg(struct edid *edid, const char mfg[static 3])
 {
 	edid->mfg_id[0] = (mfg[0] - '@') << 2 | (mfg[1] - '@') >> 3;

index 8d8e30ec0554..47581bb778b0 100644
@@ -298,6 +298,7 @@ void edid_init(struct edid *edid);
 void edid_init_with_mode(struct edid *edid, drmModeModeInfo *mode);
 void edid_update_checksum(struct edid *edid);
 size_t edid_get_size(const struct edid *edid);
+void edid_get_mfg(const struct edid *edid, char out[static 3]);
 void detailed_timing_set_mode(struct detailed_timing *dt, drmModeModeInfo *mode,
 			      int width_mm, int height_mm);
 void detailed_timing_set_monitor_range_mode(struct detailed_timing *dt,

index 175e5032c973..1d5c0ded8a56 100644
@@ -184,7 +184,7 @@ check_analog_bridge(data_t *data, struct chamelium_port *port)
 	drmModeConnector *connector = chamelium_port_get_connector(
 	    data->chamelium, port, false);
 	uint64_t edid_blob_id;
-	unsigned char *edid;
+	const struct edid *edid;
 	char edid_vendor[3];
 
 	if (chamelium_port_get_type(port) != DRM_MODE_CONNECTOR_VGA) {

@@ -198,12 +198,8 @@ check_analog_bridge(data_t *data, struct chamelium_port *port)
 	igt_assert(edid_blob = drmModeGetPropertyBlob(data->drm_fd,
 						      edid_blob_id));
 
-	edid = (unsigned char *) edid_blob->data;
-
-	edid_vendor[0] = ((edid[8] & 0x7c) >> 2) + '@';
-	edid_vendor[1] = (((edid[8] & 0x03) << 3) |
-			  ((edid[9] & 0xe0) >> 5)) + '@';
-	edid_vendor[2] = (edid[9] & 0x1f) + '@';
+	edid = (const struct edid *) edid_blob->data;
+	edid_get_mfg(edid, edid_vendor);
 
 	drmModeFreePropertyBlob(edid_blob);
 	drmModeFreeConnector(connector);

index 959a14333ed9..3cd2acafd385 100644
@@ -1758,6 +1758,50 @@ static unsigned int chamelium_get_port_type(struct chamelium *chamelium,
 	return port_type;
 }
 
+static bool chamelium_has_video_support(struct chamelium *chamelium,
+					int port_id)
+{
+	xmlrpc_value *res;
+	int has_video_support;
+
+	res = chamelium_rpc(chamelium, NULL, "HasVideoSupport", "(i)", port_id);
+	xmlrpc_read_bool(&chamelium->env, res, &has_video_support);
+	xmlrpc_DECREF(res);
+
+	return has_video_support;
+}
+
+/**
+ * chamelium_get_video_ports: retrieve a list of video port IDs
+ *
+ * Returns: the number of video port IDs
+ */
+static size_t chamelium_get_video_ports(struct chamelium *chamelium,
+					int port_ids[static CHAMELIUM_MAX_PORTS])
+{
+	xmlrpc_value *res, *res_port;
+	int res_len, i, port_id;
+	size_t port_ids_len = 0;
+
+	res = chamelium_rpc(chamelium, NULL, "GetSupportedInputs", "()");
+	res_len = xmlrpc_array_size(&chamelium->env, res);
+	for (i = 0; i < res_len; i++) {
+		xmlrpc_array_read_item(&chamelium->env, res, i, &res_port);
+		xmlrpc_read_int(&chamelium->env, res_port, &port_id);
+		xmlrpc_DECREF(res_port);
+
+		if (!chamelium_has_video_support(chamelium, port_id))
+			continue;
+
+		igt_assert(port_ids_len < CHAMELIUM_MAX_PORTS);
+		port_ids[port_ids_len] = port_id;
+		port_ids_len++;
+	}
+	xmlrpc_DECREF(res);
+
+	return port_ids_len;
+}
+
 static bool chamelium_read_port_mappings(struct chamelium *chamelium,
 					 int drm_fd)
 {

index 3cd2acafd385..05ef8bf99e67 100644
@@ -360,7 +360,7 @@ static xmlrpc_value *chamelium_rpc(struct chamelium *chamelium,
  */
 void chamelium_plug(struct chamelium *chamelium, struct chamelium_port *port)
 {
-	igt_debug("Plugging %s\n", port->name);
+	igt_debug("Plugging %s (Chamelium port ID %d)\n", port->name, port->id);
 	xmlrpc_DECREF(chamelium_rpc(chamelium, NULL, "Plug", "(i)", port->id));
 }
 

@@ -1893,6 +1893,212 @@ out:
 	return ret;
 }
 
+static int port_id_from_edid(int drm_fd, drmModeConnector *connector)
+{
+	int port_id = -1;
+	bool ok;
+	uint64_t edid_blob_id;
+	drmModePropertyBlobRes *edid_blob;
+	const struct edid *edid;
+	char mfg[3];
+
+	if (connector->connection != DRM_MODE_CONNECTED) {
+		igt_debug("Skipping auto-discovery for connector %s-%d: "
+			  "connector status is not connected\n",
+			  kmstest_connector_type_str(connector->connector_type),
+			  connector->connector_type_id);
+		return -1;
+	}
+
+	ok = kmstest_get_property(drm_fd, connector->connector_id,
+				  DRM_MODE_OBJECT_CONNECTOR, "EDID",
+				  NULL, &edid_blob_id, NULL);
+	if (!ok || !edid_blob_id) {
+		igt_debug("Skipping auto-discovery for connector %s-%d: "
+			  "missing the EDID property\n",
+			  kmstest_connector_type_str(connector->connector_type),
+			  connector->connector_type_id);
+		return -1;
+	}
+
+	edid_blob = drmModeGetPropertyBlob(drm_fd, edid_blob_id);
+	igt_assert(edid_blob);
+
+	edid = (const struct edid *) edid_blob->data;
+
+	edid_get_mfg(edid, mfg);
+	if (memcmp(mfg, "IGT", 3) != 0) {
+		igt_debug("Skipping connector %s-%d for auto-discovery: "
+			  "manufacturer is %.3s, not IGT\n",
+			  kmstest_connector_type_str(connector->connector_type),
+			  connector->connector_type_id, mfg);
+		goto out;
+	}
+
+	if (edid->prod_code[0] != 'C' || edid->prod_code[1] != 'H') {
+		igt_warn("Invalid EDID for IGT connector %s-%d: "
+			  "invalid product code\n",
+			  kmstest_connector_type_str(connector->connector_type),
+			  connector->connector_type_id);
+		goto out;
+	}
+
+	port_id = *(uint32_t *) &edid->serial;
+	igt_debug("Auto-discovery mapped connector %s-%d to Chamelium "
+		  "port ID %d\n",
+		  kmstest_connector_type_str(connector->connector_type),
+		  connector->connector_type_id, port_id);
+
+out:
+	drmModeFreePropertyBlob(edid_blob);
+	return port_id;
+}
+
+/**
+ * chamelium_autodiscover: automagically discover the Chamelium port mapping
+ *
+ * The Chamelium API uses port IDs wheras the Device Under Test uses DRM
+ * connectors. We need to know which Chamelium port is plugged to a given DRM
+ * connector. This has typically been done via a configuration file in the
+ * past (see #chamelium_read_port_mappings), but this function provides an
+ * automatic way to do it.
+ *
+ * We will plug all Chamelium ports with a different EDID on each. Then we'll
+ * read the EDID on each DRM connector and infer the Chamelium port ID.
+ */
+static bool chamelium_autodiscover(struct chamelium *chamelium, int drm_fd)
+{
+	int candidate_ports[CHAMELIUM_MAX_PORTS];
+	size_t candidate_ports_len;
+	drmModeRes *res;
+	drmModeConnector *connector;
+	struct chamelium_port *port;
+	size_t i, j, port_count;
+	int port_id;
+	uint32_t conn_id;
+	struct chamelium_edid *edid;
+	bool found;
+	uint32_t discovered_conns[CHAMELIUM_MAX_PORTS] = {0};
+	char conn_name[64];
+	struct timespec start;
+	uint64_t elapsed_ns;
+
+	candidate_ports_len = chamelium_get_video_ports(chamelium,
+							candidate_ports);
+
+	igt_debug("Starting Chamelium port auto-discovery on %zu ports\n",
+		  candidate_ports_len);
+	igt_gettime(&start);
+
+	edid = chamelium_new_edid(chamelium, igt_kms_get_base_edid());
+
+	/* Set EDID and plug ports we want to auto-discover */
+	port_count = chamelium->port_count;
+	for (i = 0; i < candidate_ports_len; i++) {
+		port_id = candidate_ports[i];
+
+		/* Get or add a chamelium_port slot */
+		port = NULL;
+		for (j = 0; j < chamelium->port_count; j++) {
+			if (chamelium->ports[j].id == port_id) {
+				port = &chamelium->ports[j];
+				break;
+			}
+		}
+		if (!port) {
+			igt_assert(port_count < CHAMELIUM_MAX_PORTS);
+			port = &chamelium->ports[port_count];
+			port_count++;
+
+			port->id = port_id;
+		}
+
+		chamelium_port_set_edid(chamelium, port, edid);
+		chamelium_plug(chamelium, port);
+	}
+
+	/* Reprobe connectors and build the mapping */
+	res = drmModeGetResources(drm_fd);
+	if (!res)
+		return false;
+
+	for (i = 0; i < res->count_connectors; i++) {
+		conn_id = res->connectors[i];
+
+		/* Read the EDID and parse the Chamelium port ID we stored
+		 * there. */
+		connector = drmModeGetConnector(drm_fd, res->connectors[i]);
+		port_id = port_id_from_edid(drm_fd, connector);
+		drmModeFreeConnector(connector);
+		if (port_id < 0)
+			continue;
+
+		/* If we already have a mapping from the config file, check
+		 * that it's consistent. */
+		found = false;
+		for (j = 0; j < chamelium->port_count; j++) {
+			port = &chamelium->ports[j];
+			if (port->connector_id == conn_id) {
+				found = true;
+				igt_assert_f(port->id == port_id,
+					     "Inconsistency detected in .igtrc: "
+					     "connector %s is configured with "
+					     "Chamelium port %d, but is "
+					     "connected to port %d\n",
+					     port->name, port->id, port_id);
+				break;
+			}
+		}
+		if (found)
+			continue;
+
+		/* We got a new mapping */
+		found = false;
+		for (j = 0; j < candidate_ports_len; j++) {
+			if (port_id == candidate_ports[j]) {
+				found = true;
+				discovered_conns[j] = conn_id;
+				break;
+			}
+		}
+		igt_assert_f(found, "Auto-discovered a port (%d) we haven't "
+			     "setup\n", port_id);
+	}
+
+	drmModeFreeResources(res);
+
+	/* We now have a Chamelium port ID ↔ DRM connector ID mapping:
+	 * candidate_ports contains the Chamelium port IDs and
+	 * discovered_conns contains the DRM connector IDs. */
+	for (i = 0; i < candidate_ports_len; i++) {
+		port_id = candidate_ports[i];
+		conn_id = discovered_conns[i];
+		if (!conn_id) {
+			continue;
+		}
+
+		port = &chamelium->ports[chamelium->port_count];
+		chamelium->port_count++;
+
+		port->id = port_id;
+		port->type = chamelium_get_port_type(chamelium, port);
+		port->connector_id = conn_id;
+
+		connector = drmModeGetConnectorCurrent(drm_fd, conn_id);
+		snprintf(conn_name, sizeof(conn_name), "%s-%u",
+			 kmstest_connector_type_str(connector->connector_type),
+			 connector->connector_type_id);
+		drmModeFreeConnector(connector);
+		port->name = strdup(conn_name);
+	}
+
+	elapsed_ns = igt_nsec_elapsed(&start);
+	igt_debug("Auto-discovery took %fms\n",
+		  (float) elapsed_ns / (1000 * 1000));
+
+	return true;
+}
+
 static bool chamelium_read_config(struct chamelium *chamelium, int drm_fd)
 {
 	GError *error = NULL;

@@ -1910,7 +2116,10 @@ static bool chamelium_read_config(struct chamelium *chamelium, int drm_fd)
 		return false;
 	}
 
-	return chamelium_read_port_mappings(chamelium, drm_fd);
+	if (!chamelium_read_port_mappings(chamelium, drm_fd)) {
+		return false;
+	}
+	return chamelium_autodiscover(chamelium, drm_fd);
 }
 
 /**