drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validationgrafted

amdgpu_dm_create_validate_stream_for_sink() walks encoding_order[] and
uses the first encoding that validates. YCbCr 4:4:4 is listed before
RGB, so an HDMI sink that advertises 4:4:4 gets YCbCr 4:4:4 whenever the
"color format" property is left at AUTO, even though RGB fits the same
link.

That contradicts the documented AUTO behaviour for HDMI in enum
drm_connector_color_format (RGB, falling back to YCbCr 4:2:0 only when
the bandwidth is not available or the mode is 4:2:0-only), which the
amdgpu implementation of the property also describes. It also leaves
the "Broadcast RGB" property without effect on such sinks, since the
quantization range it selects only applies to RGB output.

Try RGB first. The mask still holds every encoding the sink supports,
so a mode that cannot carry RGB falls back exactly as before.

For reference, v7.2 picked RGB here unless YCbCr 4:4:4 was forced
through debugfs, while earlier kernels picked YCbCr 4:4:4 for any HDMI
sink that advertised it.

Fixes: 0b0ff65d3ca1 ("drm/amd/display: Refactor stream validation")
Suggested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Assisted-by: Claude Code:claude-fable-5-1
Signed-off-by: Adrian Betschart <adrian.betschart@cinemaone.ch>
Reviewed-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7)

1 files changed, 324 insertions, 0 deletions

diff --git a/drivers/interconnect/icc-kunit.c b/drivers/interconnect/icc-kunit.c
new file mode 100644
index 000000000..bad2b5837
--- /dev/null
+++ b/drivers/interconnect/icc-kunit.c
@@ -0,0 +1,324 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests for the Interconnect framework.
+ *
+ * Copyright (c) 2025 Kuan-Wei Chiu <visitorckw@gmail.com>
+ *
+ * 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,
+	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];
+};
+
+static struct icc_node *get_node(struct icc_test_priv *priv, int id)
+{
+	int idx = id - NODE_CPU;
+
+	if (idx < 0 || idx >= ARRAY_SIZE(test_topology))
+		return NULL;
+	return priv->nodes[idx];
+}
+
+static int icc_test_set(struct icc_node *src, struct icc_node *dst)
+{
+	return 0;
+}
+
+static int icc_test_aggregate(struct icc_node *node, u32 tag, u32 avg_bw,
+			      u32 peak_bw, u32 *agg_avg, u32 *agg_peak)
+{
+	return icc_std_aggregate(node, tag, avg_bw, peak_bw, agg_avg, agg_peak);
+}
+
+static struct icc_node *icc_test_xlate(const struct of_phandle_args *spec, void *data)
+{
+	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;
+	struct icc_node *node;
+	int i, j, ret;
+
+	priv = kunit_kzalloc(test, sizeof(*priv), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv);
+	test->priv = priv;
+
+	priv->pdev = kunit_platform_device_alloc(test, "icc-test-dev", -1);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->pdev);
+	KUNIT_ASSERT_EQ(test, kunit_platform_device_add(test, priv->pdev), 0);
+
+	priv->provider.set = icc_test_set;
+	priv->provider.aggregate = icc_test_aggregate;
+	priv->provider.xlate = icc_test_xlate;
+	priv->provider.get_bw = icc_test_get_bw;
+	priv->provider.dev = &priv->pdev->dev;
+	priv->provider.data = priv;
+	INIT_LIST_HEAD(&priv->provider.nodes);
+
+	ret = icc_provider_register(&priv->provider);
+	KUNIT_ASSERT_EQ(test, ret, 0);
+
+	for (i = 0; i < ARRAY_SIZE(test_topology); i++) {
+		const struct test_node_data *data = &test_topology[i];
+
+		node = icc_node_create(data->id);
+		KUNIT_ASSERT_NOT_ERR_OR_NULL(test, node);
+
+		node->name = data->name;
+		icc_node_add(node, &priv->provider);
+		priv->nodes[i] = node;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(test_topology); i++) {
+		const struct test_node_data *data = &test_topology[i];
+		struct icc_node *src = get_node(priv, data->id);
+
+		for (j = 0; j < data->num_links; j++) {
+			ret = icc_link_create(src, data->links[j]);
+			KUNIT_ASSERT_EQ_MSG(test, ret, 0, "Failed to link %s->%d",
+					    src->name, data->links[j]);
+		}
+	}
+
+	icc_sync_state(&priv->pdev->dev);
+
+	return 0;
+}
+
+static void icc_test_exit(struct kunit *test)
+{
+	struct icc_test_priv *priv = test->priv;
+
+	icc_nodes_remove(&priv->provider);
+	icc_provider_deregister(&priv->provider);
+}
+
+/*
+ * Helper to construct a mock path.
+ *
+ * Because we are bypassing icc_get(), we must manually link the requests
+ * to the nodes' req_list so that icc_std_aggregate() can discover them.
+ */
+static struct icc_path *icc_test_create_path(struct kunit *test,
+					     struct icc_node **nodes, int num)
+{
+	struct icc_path *path;
+	int i;
+
+	path = kunit_kzalloc(test, struct_size(path, reqs, num), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, path);
+
+	path->num_nodes = num;
+	for (i = 0; i < num; i++) {
+		path->reqs[i].node = nodes[i];
+		hlist_add_head(&path->reqs[i].req_node, &nodes[i]->req_list);
+	}
+	path->name = "mock-path";
+
+	return path;
+}
+
+static void icc_test_destroy_path(struct kunit *test, struct icc_path *path)
+{
+	int i;
+
+	for (i = 0; i < path->num_nodes; i++)
+		hlist_del(&path->reqs[i].req_node);
+
+	kunit_kfree(test, path);
+}
+
+static void icc_test_topology_integrity(struct kunit *test)
+{
+	struct icc_test_priv *priv = test->priv;
+	struct icc_node *cpu = get_node(priv, NODE_CPU);
+	struct icc_node *bus = get_node(priv, NODE_BUS);
+
+	KUNIT_EXPECT_EQ(test, cpu->num_links, 1);
+	KUNIT_EXPECT_PTR_EQ(test, cpu->links[0], bus);
+	KUNIT_EXPECT_PTR_EQ(test, cpu->provider, &priv->provider);
+}
+
+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);
+}
+
+static void icc_test_aggregation(struct kunit *test)
+{
+	struct icc_test_priv *priv = test->priv;
+	struct icc_path *path_cpu, *path_gpu;
+	struct icc_node *nodes_cpu[3], *nodes_gpu[2];
+	struct icc_node *bus = get_node(priv, NODE_BUS);
+	int ret;
+
+	nodes_cpu[0] = get_node(priv, NODE_CPU);
+	nodes_cpu[1] = bus;
+	nodes_cpu[2] = get_node(priv, NODE_DDR);
+	path_cpu = icc_test_create_path(test, nodes_cpu, 3);
+
+	nodes_gpu[0] = get_node(priv, NODE_GPU);
+	nodes_gpu[1] = bus;
+	path_gpu = icc_test_create_path(test, nodes_gpu, 2);
+
+	icc_enable(path_cpu);
+	icc_enable(path_gpu);
+
+	ret = icc_set_bw(path_cpu, 1000, 1000);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, bus->avg_bw, 1000);
+
+	ret = icc_set_bw(path_gpu, 2000, 2000);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+
+	/* Bus aggregates: CPU(1000) + GPU(2000) */
+	KUNIT_EXPECT_EQ(test, bus->avg_bw, 3000);
+	/* Peak aggregates: max(CPU, GPU) */
+	KUNIT_EXPECT_EQ(test, bus->peak_bw, 2000);
+
+	icc_test_destroy_path(test, path_cpu);
+	icc_test_destroy_path(test, path_gpu);
+}
+
+static void icc_test_bulk_ops(struct kunit *test)
+{
+	struct icc_test_priv *priv = test->priv;
+	struct icc_node *nodes_cpu[3], *nodes_gpu[2];
+	struct icc_bulk_data bulk[2];
+	int ret;
+
+	nodes_cpu[0] = get_node(priv, NODE_CPU);
+	nodes_cpu[1] = get_node(priv, NODE_BUS);
+	nodes_cpu[2] = get_node(priv, NODE_DDR);
+
+	nodes_gpu[0] = get_node(priv, NODE_GPU);
+	nodes_gpu[1] = get_node(priv, NODE_BUS);
+
+	bulk[0].path = icc_test_create_path(test, nodes_cpu, 3);
+	bulk[0].avg_bw = 500;
+	bulk[0].peak_bw = 500;
+
+	bulk[1].path = icc_test_create_path(test, nodes_gpu, 2);
+	bulk[1].avg_bw = 600;
+	bulk[1].peak_bw = 600;
+
+	ret = icc_bulk_set_bw(2, bulk);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	/* Paths disabled, bandwidth should be 0 */
+	KUNIT_EXPECT_EQ(test, get_node(priv, NODE_BUS)->avg_bw, 0);
+
+	ret = icc_bulk_enable(2, bulk);
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	/* Paths enabled, aggregation applies */
+	KUNIT_EXPECT_EQ(test, get_node(priv, NODE_BUS)->avg_bw, 1100);
+
+	icc_bulk_disable(2, bulk);
+	KUNIT_EXPECT_EQ(test, get_node(priv, NODE_BUS)->avg_bw, 0);
+
+	icc_test_destroy_path(test, bulk[0].path);
+	icc_test_destroy_path(test, bulk[1].path);
+}
+
+static struct kunit_case icc_test_cases[] = {
+	KUNIT_CASE(icc_test_topology_integrity),
+	KUNIT_CASE(icc_test_set_bw),
+	KUNIT_CASE(icc_test_aggregation),
+	KUNIT_CASE(icc_test_bulk_ops),
+	{}
+};
+
+static struct kunit_suite icc_test_suite = {
+	.name = "interconnect",
+	.init = icc_test_init,
+	.exit = icc_test_exit,
+	.test_cases = icc_test_cases,
+};
+
+kunit_test_suite(icc_test_suite);
+
+MODULE_AUTHOR("Kuan-Wei Chiu <visitorckw@gmail.com>");
+MODULE_DESCRIPTION("KUnit tests for the Interconnect framework");
+MODULE_LICENSE("GPL");