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, 242 insertions, 0 deletions

diff --git a/lib/kunit/debugfs.c b/lib/kunit/debugfs.c
new file mode 100644
index 000000000..442b2ceb9
--- /dev/null
+++ b/lib/kunit/debugfs.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates.
+ *    Author: Alan Maguire <alan.maguire@oracle.com>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+
+#include <kunit/test.h>
+#include <kunit/test-bug.h>
+
+#include "string-stream.h"
+#include "debugfs.h"
+
+#define KUNIT_DEBUGFS_ROOT             "kunit"
+#define KUNIT_DEBUGFS_RESULTS          "results"
+#define KUNIT_DEBUGFS_RUN              "run"
+
+/*
+ * Create a debugfs representation of test suites:
+ *
+ * Path						Semantics
+ * /sys/kernel/debug/kunit/<testsuite>/results	Show results of last run for
+ *						testsuite
+ * /sys/kernel/debug/kunit/<testsuite>/run	Write to this file to trigger
+ *						testsuite to run
+ *
+ */
+
+static struct dentry *debugfs_rootdir;
+
+void kunit_debugfs_cleanup(void)
+{
+	debugfs_remove_recursive(debugfs_rootdir);
+}
+
+void kunit_debugfs_init(void)
+{
+	if (!debugfs_rootdir)
+		debugfs_rootdir = debugfs_create_dir(KUNIT_DEBUGFS_ROOT, NULL);
+}
+
+static void debugfs_print_result(struct seq_file *seq, struct string_stream *log)
+{
+	struct string_stream_fragment *frag_container;
+
+	if (!log)
+		return;
+
+	/*
+	 * Walk the fragments so we don't need to allocate a temporary
+	 * buffer to hold the entire string.
+	 */
+	spin_lock(&log->lock);
+	list_for_each_entry(frag_container, &log->fragments, node)
+		seq_printf(seq, "%s", frag_container->fragment);
+	spin_unlock(&log->lock);
+}
+
+/*
+ * /sys/kernel/debug/kunit/<testsuite>/results shows all results for testsuite.
+ */
+static int debugfs_print_results(struct seq_file *seq, void *v)
+{
+	struct kunit_suite *suite = (struct kunit_suite *)seq->private;
+	enum kunit_status success;
+	struct kunit_case *test_case;
+
+	if (!suite)
+		return 0;
+
+	success = kunit_suite_has_succeeded(suite);
+
+	/* Print KTAP header so the debugfs log can be parsed as valid KTAP. */
+	seq_puts(seq, "KTAP version 1\n");
+	seq_puts(seq, "1..1\n");
+
+	if (suite->status != KUNIT_SKIPPED) {
+		/* Print suite header because it is not stored in the test logs. */
+		seq_puts(seq,
+			 KUNIT_SUBTEST_INDENT "KTAP version 1\n");
+		seq_printf(seq,
+			   KUNIT_SUBTEST_INDENT "# Subtest: %s\n",
+			   suite->name);
+		seq_printf(seq,
+			   KUNIT_SUBTEST_INDENT "1..%zd\n",
+			   kunit_suite_num_test_cases(suite));
+
+		kunit_suite_for_each_test_case(suite, test_case)
+			debugfs_print_result(seq, test_case->log);
+	}
+
+	debugfs_print_result(seq, suite->log);
+
+	if (suite->status != KUNIT_SKIPPED)
+		seq_printf(seq, "%s %d %s\n",
+			   kunit_status_to_ok_not_ok(success), 1, suite->name);
+	else
+		seq_printf(seq, "%s %d %s # SKIP %s\n",
+			   kunit_status_to_ok_not_ok(success), 1, suite->name,
+			   suite->status_comment);
+	return 0;
+}
+
+static int debugfs_release(struct inode *inode, struct file *file)
+{
+	return single_release(inode, file);
+}
+
+static int debugfs_results_open(struct inode *inode, struct file *file)
+{
+	struct kunit_suite *suite;
+
+	suite = (struct kunit_suite *)inode->i_private;
+
+	return single_open(file, debugfs_print_results, suite);
+}
+
+/*
+ * Print a usage message to the debugfs "run" file
+ * (/sys/kernel/debug/kunit/<testsuite>/run) if opened.
+ */
+static int debugfs_print_run(struct seq_file *seq, void *v)
+{
+	struct kunit_suite *suite = (struct kunit_suite *)seq->private;
+
+	seq_puts(seq, "Write to this file to trigger the test suite to run.\n");
+	seq_printf(seq, "usage: echo \"any string\" > /sys/kernel/debugfs/kunit/%s/run\n",
+			suite->name);
+	return 0;
+}
+
+/*
+ * The debugfs "run" file (/sys/kernel/debug/kunit/<testsuite>/run)
+ * contains no information. Write to the file to trigger the test suite
+ * to run.
+ */
+static int debugfs_run_open(struct inode *inode, struct file *file)
+{
+	struct kunit_suite *suite;
+
+	suite = (struct kunit_suite *)inode->i_private;
+
+	return single_open(file, debugfs_print_run, suite);
+}
+
+/*
+ * Trigger a test suite to run by writing to the suite's "run" debugfs
+ * file found at: /sys/kernel/debug/kunit/<testsuite>/run
+ *
+ * Note: what is written to this file will not be saved.
+ */
+static ssize_t debugfs_run(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct inode *f_inode = file->f_inode;
+	struct kunit_suite *suite = (struct kunit_suite *) f_inode->i_private;
+
+	__kunit_test_suites_init(&suite, 1, true);
+
+	return count;
+}
+
+static const struct file_operations debugfs_results_fops = {
+	.open = debugfs_results_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = debugfs_release,
+};
+
+static const struct file_operations debugfs_run_fops = {
+	.open = debugfs_run_open,
+	.read = seq_read,
+	.write = debugfs_run,
+	.llseek = seq_lseek,
+	.release = debugfs_release,
+};
+
+void kunit_debugfs_create_suite(struct kunit_suite *suite)
+{
+	struct kunit_case *test_case;
+	struct string_stream *stream;
+
+	/* If suite log already allocated, do not create new debugfs files. */
+	if (suite->log)
+		return;
+
+	/*
+	 * Allocate logs before creating debugfs representation.
+	 * The suite->log and test_case->log pointer are expected to be NULL
+	 * if there isn't a log, so only set it if the log stream was created
+	 * successfully.
+	 */
+	stream = alloc_string_stream(GFP_KERNEL);
+	if (IS_ERR(stream))
+		return;
+
+	string_stream_set_append_newlines(stream, true);
+	suite->log = stream;
+
+	kunit_suite_for_each_test_case(suite, test_case) {
+		stream = alloc_string_stream(GFP_KERNEL);
+		if (IS_ERR(stream))
+			goto err;
+
+		string_stream_set_append_newlines(stream, true);
+		test_case->log = stream;
+	}
+
+	suite->debugfs = debugfs_create_dir(suite->name, debugfs_rootdir);
+
+	debugfs_create_file(KUNIT_DEBUGFS_RESULTS, S_IFREG | 0444,
+			    suite->debugfs,
+			    suite, &debugfs_results_fops);
+
+	/* Do not create file to re-run test if test runs on init */
+	if (!suite->is_init) {
+		debugfs_create_file(KUNIT_DEBUGFS_RUN, S_IFREG | 0644,
+				    suite->debugfs,
+				    suite, &debugfs_run_fops);
+	}
+	return;
+
+err:
+	string_stream_destroy(suite->log);
+	suite->log = NULL;
+	kunit_suite_for_each_test_case(suite, test_case) {
+		string_stream_destroy(test_case->log);
+		test_case->log = NULL;
+	}
+}
+
+void kunit_debugfs_destroy_suite(struct kunit_suite *suite)
+{
+	struct kunit_case *test_case;
+
+	debugfs_remove_recursive(suite->debugfs);
+	string_stream_destroy(suite->log);
+	kunit_suite_for_each_test_case(suite, test_case)
+		string_stream_destroy(test_case->log);
+}