[PATCH i-g-t v3 05/29] lib/igt_kms: Add helper to wait for new connectors

[Louis Chauvet]

Add list comparison utilities and a new function to wait for new
connectors to appear on the system.

Signed-off-by: Louis Chauvet <louis.chauvet at bootlin.com>
---
 lib/igt_kms.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_kms.h |  6 ++++
 2 files changed, 99 insertions(+)

diff --git a/lib/igt_kms.c b/lib/igt_kms.c
index f560fa5d540c5d610fe59a89001f3373d0a6ae47..843924e79eae1e21542b0dd916bd92627f7a8473 100644
--- a/lib/igt_kms.c
+++ b/lib/igt_kms.c
@@ -7785,3 +7785,96 @@ uint32_t igt_get_connector_id_from_mst_path(int drm_fd, const void *mst_path)
 
 	return 0;
 }
+
+/**
+ * list_contains() - Search an element in the list
+ *
+ * @list: Pointer to the list to search into
+ * @list_len: Length of the list
+ * @value: Value to search in the list
+ *
+ * Returns true if @list contains @value
+ */
+static bool list_contains(const uint32_t *list, int list_len, uint32_t value)
+{
+	igt_assert((!list && list_len == 0) || list);
+	for (int i = 0; i < list_len; i++) {
+		if (list[i] == value)
+			return true;
+	}
+	return false;
+}
+
+/**
+ * get_list_diff() - Compute and return the difference between two lists
+ *
+ * @list_a: Pointer to the first list to compare
+ * @list_a_len: Length of the first list
+ * @list_b: Pointer to the second list to compare
+ * @list_b_len: Length of the second list
+ * @diff: Out pointer for the difference. Can be null to only count new elements.
+ *
+ * Returns the number of element which are in @list_a but not in @list_b.
+ */
+int
+get_list_diff(const uint32_t *list_a, int list_a_len, const uint32_t *list_b, int list_b_len,
+	      uint32_t **diff)
+{
+	int diff_len = 0;
+
+	igt_assert((!list_a && list_a_len == 0) || list_a);
+	igt_assert((!list_b && list_b_len == 0) || list_b);
+
+	if (diff)
+		*diff = malloc(sizeof(**diff));
+
+	for (int i = 0; i < list_a_len; i++) {
+		if (!list_contains(list_b, list_b_len, list_a[i])) {
+			if (diff) {
+				*diff = reallocarray(*diff, diff_len + 1, sizeof(**diff));
+				igt_assert(*diff);
+				(*diff)[diff_len] = list_a[i];
+			}
+
+			diff_len++;
+		}
+	}
+
+	return diff_len;
+}
+
+/**
+ * kms_wait_for_new_connectors() - Wait for new connector to appear
+ *
+ * @list_a: Pointer to the first list to compare
+ * @list_a_len: Length of the first list
+ * @list_b: Pointer to the second list to compare
+ * @list_b_len: Length of the second list
+ * @diff: Out pointer for the difference. Can be null.
+ *
+ * Returns the number of element which differ between the two lists.
+ */
+int kms_wait_for_new_connectors(uint32_t **newly_connected,
+				const uint32_t *already_connected,
+				int already_connected_count, int drm_fd)
+{
+	int newly_connected_count;
+	struct timespec start, end;
+
+	igt_assert(newly_connected);
+	igt_assert(drm_fd);
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	clock_gettime(CLOCK_MONOTONIC, &end);
+	do {
+		if (*newly_connected)
+			free(*newly_connected);
+		newly_connected_count = igt_get_connected_connectors(drm_fd, newly_connected);
+		clock_gettime(CLOCK_MONOTONIC, &end);
+	} while (get_list_diff(*newly_connected, newly_connected_count,
+			       already_connected, already_connected_count,
+			       NULL) == 0 &&
+		 igt_time_elapsed(&start, &end) <= igt_default_display_detect_timeout());
+
+	return newly_connected_count;
+}
diff --git a/lib/igt_kms.h b/lib/igt_kms.h
index 1d89061d80f07d11e5fb8d91265b8c38b27a0c2c..94e9b4dec45603b26568c82cfa253c30e403b90c 100644
--- a/lib/igt_kms.h
+++ b/lib/igt_kms.h
@@ -1306,4 +1306,10 @@ drmModeConnectorPtr igt_get_connector_from_name(int drm_fd, const char *port_nam
 uint32_t igt_get_connector_id_from_name(int drm_fd, const char *port_name);
 uint32_t igt_get_connector_id_from_mst_path(int drm_fd, const void *mst_path);
 
+int kms_wait_for_new_connectors(uint32_t **newly_connected,
+				const uint32_t *already_connected,
+				int already_connected_count, int drm_fd);
+int
+get_list_diff(const uint32_t *list_a, int list_a_len, const uint32_t *list_b, int list_b_len,
+	      uint32_t **diff);
 #endif /* __IGT_KMS_H__ */

-- 
2.50.1