Re: [PATCH] interconnect: Add kunit tests for core functionality
From: Georgi Djakov
Date: Fri Jan 09 2026 - 18:09:10 EST
On 12/10/25 8:00 PM, Kuan-Wei Chiu wrote:
The interconnect framework currently lacks in-tree unit tests to verify
the core logic in isolation. This makes it difficult to validate
regression stability when modifying the provider/consumer APIs or
aggregation logic.
Introduce a kunit test suite that verifies the fundamental behavior of
the subsystem. The tests cover:
- Provider API (node creation, linking, topology construction).
- Consumer API (path enabling/disabling, bandwidth requests).
- Standard aggregation logic (accumulating bandwidth across links).
- Bulk operations for setting bandwidth on multiple paths.
The suite simulates a simple SoC topology with multiple masters and a
shared bus to validate traffic aggregation behavior in a controlled
software environment, without requiring specific hardware or Device
Tree support.
Signed-off-by: Kuan-Wei Chiu <visitorckw@xxxxxxxxx>
---
Build and kunit tests passed
drivers/interconnect/Kconfig | 14 ++
drivers/interconnect/Makefile | 2 +
drivers/interconnect/icc-kunit.c | 315 +++++++++++++++++++++++++++++++
3 files changed, 331 insertions(+)
create mode 100644 drivers/interconnect/icc-kunit.c
diff --git a/drivers/interconnect/Kconfig b/drivers/interconnect/Kconfig
index f2e49bd97d31..882dcb0b4a5b 100644
--- a/drivers/interconnect/Kconfig
+++ b/drivers/interconnect/Kconfig
@@ -22,4 +22,18 @@ config INTERCONNECT_CLK
help
Support for wrapping clocks into the interconnect nodes.
+config INTERCONNECT_KUNIT_TEST
+ tristate "KUnit tests for Interconnect framework"
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+ help
+ This builds the KUnit test suite for the generic system interconnect
+ framework.
+
+ The tests cover the core functionality of the interconnect subsystem,
+ including provider/consumer APIs, topology management, and bandwidth
+ aggregation logic.
+
+ If unsure, say N.
+
endif
diff --git a/drivers/interconnect/Makefile b/drivers/interconnect/Makefile
index b0a9a6753b9d..dc4c7b657c9d 100644
--- a/drivers/interconnect/Makefile
+++ b/drivers/interconnect/Makefile
@@ -10,3 +10,5 @@ obj-$(CONFIG_INTERCONNECT_QCOM) += qcom/
obj-$(CONFIG_INTERCONNECT_SAMSUNG) += samsung/
obj-$(CONFIG_INTERCONNECT_CLK) += icc-clk.o
+
+obj-$(CONFIG_INTERCONNECT_KUNIT_TEST) += icc-kunit.o
diff --git a/drivers/interconnect/icc-kunit.c b/drivers/interconnect/icc-kunit.c
new file mode 100644
index 000000000000..2178487f9527
--- /dev/null
+++ b/drivers/interconnect/icc-kunit.c
@@ -0,0 +1,315 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests for the Interconnect framework.
+ *
+ * Copyright (c) 2025 Kuan-Wei Chiu <visitorckw@xxxxxxxxx>
+ *
+ * This suite verifies the behavior of the interconnect core, including
+ * topology construction, bandwidth aggregation, and path lifecycle.
+ */
+
+#include <kunit/platform_device.h>
+#include <kunit/test.h>
+#include <linux/interconnect-provider.h>
+#include <linux/interconnect.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include "internal.h"
+
+enum {
+ NODE_CPU = 100,
+ NODE_GPU,
+ NODE_BUS,
+ NODE_DDR,
+ NODE_MAX
+};
+
+struct test_node_data {
+ int id;
+ const char *name;
+ int num_links;
+ int links[2];
+};
+
+/*
+ * Static Topology:
+ * CPU -\
+ * -> BUS -> DDR
+ * GPU -/
+ */
+static const struct test_node_data test_topology[] = {
+ { NODE_CPU, "cpu", 1, { NODE_BUS } },
+ { NODE_GPU, "gpu", 1, { NODE_BUS } },
+ { NODE_BUS, "bus", 1, { NODE_DDR } },
+ { NODE_DDR, "ddr", 0, { } },
+};
+
+struct icc_test_priv {
+ struct icc_provider provider;
+ struct platform_device *pdev;
+ struct icc_node *nodes[NODE_MAX];
So nodes[] is a 104-element array? Is this intentional?
[..]
+static void icc_test_set_bw(struct kunit *test)
+{
+ struct icc_test_priv *priv = test->priv;
+ struct icc_path *path;
+ struct icc_node *path_nodes[3];
+ int ret;
+
+ /* Path: CPU -> BUS -> DDR */
+ path_nodes[0] = get_node(priv, NODE_CPU);
+ path_nodes[1] = get_node(priv, NODE_BUS);
+ path_nodes[2] = get_node(priv, NODE_DDR);
+
+ path = icc_test_create_path(test, path_nodes, 3);
+
+ ret = icc_enable(path);
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
+ ret = icc_set_bw(path, 1000, 2000);
+ KUNIT_EXPECT_EQ(test, ret, 0);
+
+ KUNIT_EXPECT_EQ(test, path_nodes[0]->avg_bw, 1000);
+ KUNIT_EXPECT_EQ(test, path_nodes[0]->peak_bw, 2000);
+ KUNIT_EXPECT_EQ(test, path_nodes[1]->avg_bw, 1000);
+ KUNIT_EXPECT_EQ(test, path_nodes[1]->peak_bw, 2000);
+
+ icc_set_tag(path, 0xABC);
+ KUNIT_EXPECT_EQ(test, path->reqs[0].tag, 0xABC);
+
+ icc_disable(path);
+ KUNIT_EXPECT_EQ(test, path_nodes[0]->avg_bw, 0);
+
+ icc_test_destroy_path(test, path);
+}
+
I also tried to run it and noticed that one of the tests is failing on my board...
KTAP version 1
1..1
KTAP version 1
# Subtest: interconnect
1..4
ok 1 icc_test_topology_integrity
# icc_test_set_bw: EXPECTATION FAILED at drivers/interconnect/icc-kunit.c:207
Expected path_nodes[0]->avg_bw == 1000, but
path_nodes[0]->avg_bw == 2147483647 (0x7fffffff)
# icc_test_set_bw: EXPECTATION FAILED at drivers/interconnect/icc-kunit.c:208
Expected path_nodes[0]->peak_bw == 2000, but
path_nodes[0]->peak_bw == 2147483647 (0x7fffffff)
# icc_test_set_bw: EXPECTATION FAILED at drivers/interconnect/icc-kunit.c:209
Expected path_nodes[1]->avg_bw == 1000, but
path_nodes[1]->avg_bw == 2147483647 (0x7fffffff)
# icc_test_set_bw: EXPECTATION FAILED at drivers/interconnect/icc-kunit.c:210
Expected path_nodes[1]->peak_bw == 2000, but
path_nodes[1]->peak_bw == 2147483647 (0x7fffffff)
# icc_test_set_bw: EXPECTATION FAILED at drivers/interconnect/icc-kunit.c:216
Expected path_nodes[0]->avg_bw == 0, but
path_nodes[0]->avg_bw == 2147483647 (0x7fffffff)
not ok 2 icc_test_set_bw
ok 3 icc_test_aggregation
ok 4 icc_test_bulk_ops
# module: icc_kunit
# interconnect: pass:3 fail:1 skip:0 total:4
# Totals: pass:3 fail:1 skip:0 total:4
not ok 1 interconnect
...and the following diff seem to fix it:
diff --git a/drivers/interconnect/icc-kunit.c b/drivers/interconnect/icc-kunit.c
index 2178487f9527..060f640818a5 100644
--- a/drivers/interconnect/icc-kunit.c
+++ b/drivers/interconnect/icc-kunit.c
@@ -79,6 +79,14 @@ static struct icc_node *icc_test_xlate(const struct of_phandle_args *spec, void
return NULL;
}
+static int icc_test_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
+{
+ *avg = 0;
+ *peak = 0;
+
+ return 0;
+}
+
static int icc_test_init(struct kunit *test)
{
struct icc_test_priv *priv;
@@ -95,6 +103,7 @@ static int icc_test_init(struct kunit *test)
priv->provider.set = icc_test_set;
priv->provider.aggregate = icc_test_aggregate;
+ priv->provider.get_bw = icc_test_get_bw;
priv->provider.xlate = icc_test_xlate;
priv->provider.dev = &priv->pdev->dev;
priv->provider.data = priv;
Could you please update and re-send?
Thanks,
Georgi