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, 182 insertions, 0 deletions

diff --git a/lib/tests/random32_kunit.c b/lib/tests/random32_kunit.c
new file mode 100644
index 000000000..0b4af2b09
--- /dev/null
+++ b/lib/tests/random32_kunit.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Test cases for random32 functions.
+ */
+
+#include <linux/prandom.h>
+#include <kunit/test.h>
+
+/* prandom_warmup() is static in lib/random32.c; exposed for testing only. */
+void prandom_warmup(struct rnd_state *state);
+
+static const struct prandom_test1 {
+	u32 seed;
+	u32 result;
+} test1[] = {
+	{ 1U, 3484351685U },
+	{ 2U, 2623130059U },
+	{ 3U, 3125133893U },
+	{ 4U,  984847254U },
+};
+
+static const struct prandom_test2 {
+	u32 seed;
+	u32 iteration;
+	u32 result;
+} test2[] = {
+	/* Test cases against taus113 from GSL library. */
+	{  931557656U, 959U, 2975593782U },
+	{ 1339693295U, 876U, 3887776532U },
+	{ 1545556285U, 961U, 1615538833U },
+	{  601730776U, 723U, 1776162651U },
+	{ 1027516047U, 687U,  511983079U },
+	{  416526298U, 700U,  916156552U },
+	{ 1395522032U, 652U, 2222063676U },
+	{  366221443U, 617U, 2992857763U },
+	{ 1539836965U, 714U, 3783265725U },
+	{  556206671U, 994U,  799626459U },
+	{  684907218U, 799U,  367789491U },
+	{ 2121230701U, 931U, 2115467001U },
+	{ 1668516451U, 644U, 3620590685U },
+	{  768046066U, 883U, 2034077390U },
+	{ 1989159136U, 833U, 1195767305U },
+	{  536585145U, 996U, 3577259204U },
+	{ 1008129373U, 642U, 1478080776U },
+	{ 1740775604U, 939U, 1264980372U },
+	{ 1967883163U, 508U,   10734624U },
+	{ 1923019697U, 730U, 3821419629U },
+	{  442079932U, 560U, 3440032343U },
+	{ 1961302714U, 845U,  841962572U },
+	{ 2030205964U, 962U, 1325144227U },
+	{ 1160407529U, 507U,  240940858U },
+	{  635482502U, 779U, 4200489746U },
+	{ 1252788931U, 699U,  867195434U },
+	{ 1961817131U, 719U,  668237657U },
+	{ 1071468216U, 983U,  917876630U },
+	{ 1281848367U, 932U, 1003100039U },
+	{  582537119U, 780U, 1127273778U },
+	{ 1973672777U, 853U, 1071368872U },
+	{ 1896756996U, 762U, 1127851055U },
+	{  847917054U, 500U, 1717499075U },
+	{ 1240520510U, 951U, 2849576657U },
+	{ 1685071682U, 567U, 1961810396U },
+	{ 1516232129U, 557U,    3173877U },
+	{ 1208118903U, 612U, 1613145022U },
+	{ 1817269927U, 693U, 4279122573U },
+	{ 1510091701U, 717U,  638191229U },
+	{  365916850U, 807U,  600424314U },
+	{  399324359U, 702U, 1803598116U },
+	{ 1318480274U, 779U, 2074237022U },
+	{  697758115U, 840U, 1483639402U },
+	{ 1696507773U, 840U,  577415447U },
+	{ 2081979121U, 981U, 3041486449U },
+	{  955646687U, 742U, 3846494357U },
+	{ 1250683506U, 749U,  836419859U },
+	{  595003102U, 534U,  366794109U },
+	{   47485338U, 558U, 3521120834U },
+	{  619433479U, 610U, 3991783875U },
+	{  704096520U, 518U, 4139493852U },
+	{ 1712224984U, 606U, 2393312003U },
+	{ 1318233152U, 922U, 3880361134U },
+	{  855572992U, 761U, 1472974787U },
+	{   64721421U, 703U,  683860550U },
+	{  678931758U, 840U,  380616043U },
+	{  692711973U, 778U, 1382361947U },
+	{  677703619U, 530U, 2826914161U },
+	{   92393223U, 586U, 1522128471U },
+	{ 1222592920U, 743U, 3466726667U },
+	{  358288986U, 695U, 1091956998U },
+	{ 1935056945U, 958U,  514864477U },
+	{  735675993U, 990U, 1294239989U },
+	{ 1560089402U, 897U, 2238551287U },
+	{   70616361U, 829U,   22483098U },
+	{  368234700U, 731U, 2913875084U },
+	{   20221190U, 879U, 1564152970U },
+	{  539444654U, 682U, 1835141259U },
+	{ 1314987297U, 840U, 1801114136U },
+	{ 2019295544U, 645U, 3286438930U },
+	{  469023838U, 716U, 1637918202U },
+	{ 1843754496U, 653U, 2562092152U },
+	{  400672036U, 809U, 4264212785U },
+	{  404722249U, 965U, 2704116999U },
+	{  600702209U, 758U,  584979986U },
+	{  519953954U, 667U, 2574436237U },
+	{ 1658071126U, 694U, 2214569490U },
+	{  420480037U, 749U, 3430010866U },
+	{  690103647U, 969U, 3700758083U },
+	{ 1029424799U, 937U, 3787746841U },
+	{ 2012608669U, 506U, 3362628973U },
+	{ 1535432887U, 998U,   42610943U },
+	{ 1330635533U, 857U, 3040806504U },
+	{ 1223800550U, 539U, 3954229517U },
+	{ 1322411537U, 680U, 3223250324U },
+	{ 1877847898U, 945U, 2915147143U },
+	{ 1646356099U, 874U,  965988280U },
+	{  805687536U, 744U, 4032277920U },
+	{ 1948093210U, 633U, 1346597684U },
+	{  392609744U, 783U, 1636083295U },
+	{  690241304U, 770U, 1201031298U },
+	{ 1360302965U, 696U, 1665394461U },
+	{ 1220090946U, 780U, 1316922812U },
+	{  447092251U, 500U, 3438743375U },
+	{ 1613868791U, 592U,  828546883U },
+	{  523430951U, 548U, 2552392304U },
+	{  726692899U, 810U, 1656872867U },
+	{ 1364340021U, 836U, 3710513486U },
+	{ 1986257729U, 931U,  935013962U },
+	{  407983964U, 921U,  728767059U },
+};
+
+static void prandom_state_test_seed(struct rnd_state *state, u32 seed)
+{
+#define LCG(x)	 ((x) * 69069U)	/* super-duper LCG */
+	state->s1 = __seed(LCG(seed),        2U);
+	state->s2 = __seed(LCG(state->s1),   8U);
+	state->s3 = __seed(LCG(state->s2),  16U);
+	state->s4 = __seed(LCG(state->s3), 128U);
+}
+
+static void test_prandom_seed_boundary(struct kunit *test)
+{
+	int i;
+	struct rnd_state state;
+
+	for (i = 0; i < ARRAY_SIZE(test1); i++) {
+		prandom_state_test_seed(&state, test1[i].seed);
+		prandom_warmup(&state);
+		KUNIT_EXPECT_EQ(test, test1[i].result, prandom_u32_state(&state));
+	}
+}
+
+static void test_prandom_taus113(struct kunit *test)
+{
+	int i, j;
+	struct rnd_state state;
+
+	for (i = 0; i < ARRAY_SIZE(test2); i++) {
+		prandom_state_test_seed(&state, test2[i].seed);
+		prandom_warmup(&state);
+
+		for (j = 0; j < test2[i].iteration - 1; j++)
+			prandom_u32_state(&state);
+
+		KUNIT_EXPECT_EQ(test, test2[i].result, prandom_u32_state(&state));
+	}
+}
+
+static struct kunit_case prandom_test_cases[] = {
+	KUNIT_CASE(test_prandom_seed_boundary),
+	KUNIT_CASE(test_prandom_taus113),
+	{}
+};
+
+static struct kunit_suite prandom_test_suite = {
+	.name = "prandom",
+	.test_cases = prandom_test_cases,
+};
+
+kunit_test_suite(prandom_test_suite);
+
+MODULE_DESCRIPTION("KUnit test for prandom");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");