Re: [i-g-t,2/6] lib/igt_connector_helper: Add generic connector helpers

["Murthy, Arun R" <arun.r.murthy@intel.com>]

On 26-02-2026 02:58, Kunal Joshi wrote:
> Add a lightweight helper library for DRM connector operations used
> by USB4 switch and other dock/undock tests:
>
>   - igt_connector_get_connected(): enumerate connected connectors
>   - igt_connector_get_info(): query name, EDID serial, and MST path
>   - igt_connector_find_by_path(): PATH-based connector lookup (MST)
>   - igt_connector_find_by_name(): name-based connector lookup
>   - igt_connector_reprobe_all(): force reprobe all connectors by
>     iterating each connector to trigger DRM core re-detection
>
> These helpers abstract common DRM connector patterns that are needed
> by multiple test suites for display enumeration and verification.
The contents of these are already present in lib/igt__kms.c

Instead of a new file, can these be exported from lib/igt_kms.c ?


Thanks and Regards,
Arun R Murthy
-------------------

>
> Signed-off-by: Kunal Joshi <kunal1.joshi@intel.com>
> ---
>   lib/igt_connector_helper.c | 299 +++++++++++++++++++++++++++++++++++++
>   lib/igt_connector_helper.h |  27 ++++
>   lib/meson.build            |   1 +
>   3 files changed, 327 insertions(+)
>   create mode 100644 lib/igt_connector_helper.c
>   create mode 100644 lib/igt_connector_helper.h
>
> diff --git a/lib/igt_connector_helper.c b/lib/igt_connector_helper.c
> new file mode 100644
> index 000000000..6be849b7a
> --- /dev/null
> +++ b/lib/igt_connector_helper.c
> @@ -0,0 +1,299 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2026 Intel Corporation
> + */
> +
> +/**
> + * SECTION:igt_connector_helper
> + * @short_description: Generic connector helper functions for DRM/KMS
> + * @title: Connector Helper
> + * @include: igt_connector_helper.h
> + *
> + * Helper functions for DRM connector operations including enumeration,
> + * lookup by name/path, and EDID serial extraction.
> + */
> +
> +#include <string.h>
> +#include <xf86drm.h>
> +#include <xf86drmMode.h>
> +
> +#include "igt_core.h"
> +#include "igt_edid.h"
> +#include "igt_kms.h"
> +#include "igt_connector_helper.h"
> +
> +/**
> + * igt_connector_get_connected:
> + * @drm_fd: DRM file descriptor
> + * @connectors: array to store connector IDs; must be valid if @max_connectors > 0
> + * @max_connectors: maximum number of connectors to store
> + *
> + * Walks all DRM connectors and stores the IDs of those currently connected.
> + * Scanning stops once @max_connectors IDs have been collected; later
> + * connectors are not examined.
> + *
> + * Returns: number of connector IDs written to @connectors, capped by
> + * @max_connectors.
> + */
> +int igt_connector_get_connected(int drm_fd, uint32_t *connectors,
> +				int max_connectors)
> +{
> +	drmModeRes *res;
> +	drmModeConnector *conn;
> +	int count = 0;
> +	int i;
> +
> +	igt_assert(max_connectors >= 0);
> +	if (max_connectors > 0)
> +		igt_assert(connectors);
> +
> +	res = drmModeGetResources(drm_fd);
> +	if (!res)
> +		return 0;
> +
> +	for (i = 0; i < res->count_connectors && count < max_connectors; i++) {
> +		conn = drmModeGetConnector(drm_fd, res->connectors[i]);
> +		if (!conn)
> +			continue;
> +
> +		if (conn->connection == DRM_MODE_CONNECTED)
> +			connectors[count++] = conn->connector_id;
> +
> +		drmModeFreeConnector(conn);
> +	}
> +
> +	drmModeFreeResources(res);
> +	return count;
> +}
> +
> +/**
> + * igt_connector_get_info:
> + * @drm_fd: DRM file descriptor
> + * @connector_id: connector ID
> + * @name: buffer for connector name (mandatory)
> + * @name_size: size of @name; must be > 0
> + * @serial: buffer for EDID-derived serial (mandatory)
> + * @serial_size: size of @serial; must be > 1
> + * @path: buffer for MST PATH property (optional, may be NULL)
> + * @path_size: size of @path buffer
> + *
> + * Fills connector name, MST PATH, and EDID-derived serial for a connector.
> + * @name is always filled when the connector is found. @serial is filled from
> + * the ASCII serial string descriptor (0xFF) if present, else from the 32-bit
> + * header serial number; left empty if no EDID is available. @path is filled
> + * only if requested and the PATH property exists.
> + *
> + * Success means the connector object was found and @name was filled.
> + * @serial and @path are best-effort and may still be empty on success.
> + *
> + * Returns: true if the connector was found, false otherwise.
> + */
> +bool igt_connector_get_info(int drm_fd, uint32_t connector_id,
> +			    char *name, size_t name_size,
> +			    char *serial, size_t serial_size,
> +			    char *path, size_t path_size)
> +{
> +	drmModeConnector *conn;
> +	drmModePropertyBlobPtr edid_blob = NULL;
> +	uint64_t blob_id = 0;
> +	drmModePropertyPtr prop;
> +	const struct edid *edid;
> +	int i;
> +
> +	igt_assert(name && name_size > 0);
> +	igt_assert(serial && serial_size > 1);
> +	igt_assert(!path || path_size > 0);
> +
> +	name[0] = '\0';
> +	serial[0] = '\0';
> +	if (path)
> +		path[0] = '\0';
> +
> +	conn = drmModeGetConnector(drm_fd, connector_id);
> +	if (!conn)
> +		return false;
> +
> +	snprintf(name, name_size, "%s-%d",
> +		 kmstest_connector_type_str(conn->connector_type),
> +		 conn->connector_type_id);
> +
> +	for (i = 0; i < conn->count_props; i++) {
> +		prop = drmModeGetProperty(drm_fd, conn->props[i]);
> +		if (!prop)
> +			continue;
> +
> +		if (strcmp(prop->name, "EDID") == 0)
> +			blob_id = conn->prop_values[i];
> +
> +		drmModeFreeProperty(prop);
> +		if (blob_id)
> +			break;
> +	}
> +
> +	/* Extract MST PATH if requested */
> +	if (path) {
> +		drmModePropertyBlobPtr path_blob;
> +
> +		/* PATH blob payload is a NUL-terminated string */
> +		path_blob = kmstest_get_path_blob(drm_fd, connector_id);
> +		if (path_blob) {
> +			snprintf(path, path_size, "%s",
> +				 (const char *)path_blob->data);
> +			drmModeFreePropertyBlob(path_blob);
> +		}
> +	}
> +
> +	drmModeFreeConnector(conn);
> +
> +	if (blob_id) {
> +		edid_blob = drmModeGetPropertyBlob(drm_fd, blob_id);
> +		if (edid_blob) {
> +			if (edid_blob->length >= sizeof(struct edid)) {
> +				edid = edid_blob->data;
> +				edid_get_any_serial(edid, serial, serial_size);
> +			}
> +			drmModeFreePropertyBlob(edid_blob);
> +		}
> +	}
> +
> +	return true;
> +}
> +
> +/**
> + * igt_connector_find_by_path:
> + * @drm_fd: DRM file descriptor
> + * @path: MST PATH property value to match
> + * @connector_id: output for connector ID (filled on success)
> + *
> + * Finds the currently connected connector whose PATH property matches @path
> + * (exact string comparison).  PATH is the preferred stable identity for MST
> + * connectors; connector IDs may change across hotplug events.
> + *
> + * Returns: true if a matching connected connector was found.
> + */
> +bool igt_connector_find_by_path(int drm_fd, const char *path,
> +				uint32_t *connector_id)
> +{
> +	drmModeRes *res;
> +	drmModeConnector *conn;
> +	drmModePropertyBlobPtr path_blob;
> +	bool found = false;
> +	int i;
> +
> +	if (!path || !connector_id)
> +		return false;
> +
> +	res = drmModeGetResources(drm_fd);
> +	if (!res)
> +		return false;
> +
> +	for (i = 0; i < res->count_connectors && !found; i++) {
> +		conn = drmModeGetConnector(drm_fd, res->connectors[i]);
> +		if (!conn)
> +			continue;
> +
> +		if (conn->connection == DRM_MODE_CONNECTED) {
> +			path_blob = kmstest_get_path_blob(drm_fd,
> +							  conn->connector_id);
> +			if (path_blob) {
> +				if (strcmp(path_blob->data, path) == 0) {
> +					*connector_id = conn->connector_id;
> +					found = true;
> +				}
> +				drmModeFreePropertyBlob(path_blob);
> +			}
> +		}
> +
> +		drmModeFreeConnector(conn);
> +	}
> +
> +	drmModeFreeResources(res);
> +
> +	if (found)
> +		igt_debug("igt_connector: Found connector %u for path '%s'\n",
> +			  *connector_id, path);
> +
> +	return found;
> +}
> +
> +/**
> + * igt_connector_find_by_name:
> + * @drm_fd: DRM file descriptor
> + * @name: connector name to match (e.g., "DP-6")
> + * @connector_id: output for connector ID (filled on success)
> + *
> + * Name-based lookup helper.  Prefer igt_connector_find_by_path() for MST
> + * connectors, since connector names and IDs may change across hotplug events.
> + *
> + * Returns: true if a matching connected connector was found.
> + */
> +bool igt_connector_find_by_name(int drm_fd, const char *name,
> +				uint32_t *connector_id)
> +{
> +	drmModeRes *res;
> +	drmModeConnector *conn;
> +	char conn_name[IGT_CONNECTOR_NAME_MAX];
> +	bool found = false;
> +	int i;
> +
> +	if (!name || !connector_id)
> +		return false;
> +
> +	res = drmModeGetResources(drm_fd);
> +	if (!res)
> +		return false;
> +
> +	for (i = 0; i < res->count_connectors && !found; i++) {
> +		conn = drmModeGetConnector(drm_fd, res->connectors[i]);
> +		if (!conn)
> +			continue;
> +
> +		snprintf(conn_name, sizeof(conn_name), "%s-%d",
> +			 kmstest_connector_type_str(conn->connector_type),
> +			 conn->connector_type_id);
> +
> +		if (strcmp(conn_name, name) == 0 &&
> +		    conn->connection == DRM_MODE_CONNECTED) {
> +			*connector_id = conn->connector_id;
> +			found = true;
> +		}
> +
> +		drmModeFreeConnector(conn);
> +	}
> +
> +	drmModeFreeResources(res);
> +
> +	if (found)
> +		igt_debug("igt_connector: Found connector %u for name '%s'\n",
> +			  *connector_id, name);
> +
> +	return found;
> +}
> +
> +/**
> + * igt_connector_reprobe_all:
> + * @drm_fd: DRM file descriptor
> + *
> + * Issues a GETCONNECTOR ioctl for every connector, requesting fresh state
> + * from the kernel. This is often sufficient to refresh connector status and
> + * MST topology visibility after hotplug events, but does not guarantee a
> + * full hardware reprobe in all driver paths.
> + */
> +void igt_connector_reprobe_all(int drm_fd)
> +{
> +	drmModeRes *res;
> +	drmModeConnector *conn;
> +	int i;
> +
> +	res = drmModeGetResources(drm_fd);
> +	if (!res)
> +		return;
> +
> +	for (i = 0; i < res->count_connectors; i++) {
> +		conn = drmModeGetConnector(drm_fd, res->connectors[i]);
> +		if (conn)
> +			drmModeFreeConnector(conn);
> +	}
> +
> +	drmModeFreeResources(res);
> +}
> diff --git a/lib/igt_connector_helper.h b/lib/igt_connector_helper.h
> new file mode 100644
> index 000000000..fffb2661b
> --- /dev/null
> +++ b/lib/igt_connector_helper.h
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2026 Intel Corporation
> + */
> +
> +#ifndef IGT_CONNECTOR_HELPER_H
> +#define IGT_CONNECTOR_HELPER_H
> +
> +#include <stdbool.h>
> +#include <stddef.h>
> +#include <stdint.h>
> +
> +#define IGT_CONNECTOR_NAME_MAX 32
> +
> +int igt_connector_get_connected(int drm_fd, uint32_t *connectors,
> +				int max_connectors);
> +bool igt_connector_get_info(int drm_fd, uint32_t connector_id,
> +			    char *name, size_t name_size,
> +			    char *serial, size_t serial_size,
> +			    char *path, size_t path_size);
> +bool igt_connector_find_by_path(int drm_fd, const char *path,
> +				uint32_t *connector_id);
> +bool igt_connector_find_by_name(int drm_fd, const char *name,
> +				uint32_t *connector_id);
> +void igt_connector_reprobe_all(int drm_fd);
> +
> +#endif /* IGT_CONNECTOR_HELPER_H */
> diff --git a/lib/meson.build b/lib/meson.build
> index ea721ecf7..074b21fdf 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -113,6 +113,7 @@ lib_sources = [
>   	'igt_vmwgfx.c',
>   	'igt_psr.c',
>   	'igt_amd.c',
> +	'igt_connector_helper.c',
>   	'igt_edid.c',
>   	'igt_eld.c',
>   	'igt_infoframe.c',