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, 239 insertions, 0 deletions

diff --git a/lib/error-inject.c b/lib/error-inject.c
new file mode 100644
index 000000000..32f3d1ca9
--- /dev/null
+++ b/lib/error-inject.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0
+// error-inject.c: Function-level error injection table
+#include <linux/error-injection.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <asm/sections.h>
+
+/* Whitelist of symbols that can be overridden for error injection. */
+static LIST_HEAD(error_injection_list);
+static DEFINE_MUTEX(ei_mutex);
+struct ei_entry {
+	struct list_head list;
+	unsigned long start_addr;
+	unsigned long end_addr;
+	int etype;
+	void *priv;
+};
+
+bool within_error_injection_list(unsigned long addr)
+{
+	struct ei_entry *ent;
+	bool ret = false;
+
+	mutex_lock(&ei_mutex);
+	list_for_each_entry(ent, &error_injection_list, list) {
+		if (addr >= ent->start_addr && addr < ent->end_addr) {
+			ret = true;
+			break;
+		}
+	}
+	mutex_unlock(&ei_mutex);
+	return ret;
+}
+
+int get_injectable_error_type(unsigned long addr)
+{
+	struct ei_entry *ent;
+	int ei_type = -EINVAL;
+
+	mutex_lock(&ei_mutex);
+	list_for_each_entry(ent, &error_injection_list, list) {
+		if (addr >= ent->start_addr && addr < ent->end_addr) {
+			ei_type = ent->etype;
+			break;
+		}
+	}
+	mutex_unlock(&ei_mutex);
+
+	return ei_type;
+}
+
+/*
+ * Lookup and populate the error_injection_list.
+ *
+ * For safety reasons we only allow certain functions to be overridden with
+ * bpf_error_injection, so we need to populate the list of the symbols that have
+ * been marked as safe for overriding.
+ */
+static void populate_error_injection_list(struct error_injection_entry *start,
+					  struct error_injection_entry *end,
+					  void *priv)
+{
+	struct error_injection_entry *iter;
+	struct ei_entry *ent;
+	unsigned long entry, offset = 0, size = 0;
+
+	mutex_lock(&ei_mutex);
+	for (iter = start; iter < end; iter++) {
+		entry = (unsigned long)dereference_symbol_descriptor((void *)iter->addr);
+
+		if (!kernel_text_address(entry) ||
+		    !kallsyms_lookup_size_offset(entry, &size, &offset)) {
+			pr_err("Failed to find error inject entry at %p\n",
+				(void *)entry);
+			continue;
+		}
+
+		ent = kmalloc_obj(*ent);
+		if (!ent)
+			break;
+		ent->start_addr = entry;
+		ent->end_addr = entry + size;
+		ent->etype = iter->etype;
+		ent->priv = priv;
+		INIT_LIST_HEAD(&ent->list);
+		list_add_tail(&ent->list, &error_injection_list);
+	}
+	mutex_unlock(&ei_mutex);
+}
+
+/* Markers of the _error_inject_whitelist section */
+extern struct error_injection_entry __start_error_injection_whitelist[];
+extern struct error_injection_entry __stop_error_injection_whitelist[];
+
+static void __init populate_kernel_ei_list(void)
+{
+	populate_error_injection_list(__start_error_injection_whitelist,
+				      __stop_error_injection_whitelist,
+				      NULL);
+}
+
+#ifdef CONFIG_MODULES
+static void module_load_ei_list(struct module *mod)
+{
+	if (!mod->num_ei_funcs)
+		return;
+
+	populate_error_injection_list(mod->ei_funcs,
+				      mod->ei_funcs + mod->num_ei_funcs, mod);
+}
+
+static void module_unload_ei_list(struct module *mod)
+{
+	struct ei_entry *ent, *n;
+
+	if (!mod->num_ei_funcs)
+		return;
+
+	mutex_lock(&ei_mutex);
+	list_for_each_entry_safe(ent, n, &error_injection_list, list) {
+		if (ent->priv == mod) {
+			list_del_init(&ent->list);
+			kfree(ent);
+		}
+	}
+	mutex_unlock(&ei_mutex);
+}
+
+/* Module notifier call back, checking error injection table on the module */
+static int ei_module_callback(struct notifier_block *nb,
+			      unsigned long val, void *data)
+{
+	struct module *mod = data;
+
+	if (val == MODULE_STATE_COMING)
+		module_load_ei_list(mod);
+	else if (val == MODULE_STATE_GOING)
+		module_unload_ei_list(mod);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block ei_module_nb = {
+	.notifier_call = ei_module_callback,
+	.priority = 0
+};
+
+static __init int module_ei_init(void)
+{
+	return register_module_notifier(&ei_module_nb);
+}
+#else /* !CONFIG_MODULES */
+#define module_ei_init()	(0)
+#endif
+
+/*
+ * error_injection/whitelist -- shows which functions can be overridden for
+ * error injection.
+ */
+static void *ei_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&ei_mutex);
+	return seq_list_start(&error_injection_list, *pos);
+}
+
+static void ei_seq_stop(struct seq_file *m, void *v)
+{
+	mutex_unlock(&ei_mutex);
+}
+
+static void *ei_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &error_injection_list, pos);
+}
+
+static const char *error_type_string(int etype)
+{
+	switch (etype) {
+	case EI_ETYPE_NULL:
+		return "NULL";
+	case EI_ETYPE_ERRNO:
+		return "ERRNO";
+	case EI_ETYPE_ERRNO_NULL:
+		return "ERRNO_NULL";
+	case EI_ETYPE_TRUE:
+		return "TRUE";
+	default:
+		return "(unknown)";
+	}
+}
+
+static int ei_seq_show(struct seq_file *m, void *v)
+{
+	struct ei_entry *ent = list_entry(v, struct ei_entry, list);
+
+	seq_printf(m, "%ps\t%s\n", (void *)ent->start_addr,
+		   error_type_string(ent->etype));
+	return 0;
+}
+
+static const struct seq_operations ei_sops = {
+	.start = ei_seq_start,
+	.next  = ei_seq_next,
+	.stop  = ei_seq_stop,
+	.show  = ei_seq_show,
+};
+
+DEFINE_SEQ_ATTRIBUTE(ei);
+
+static int __init ei_debugfs_init(void)
+{
+	struct dentry *dir, *file;
+
+	dir = debugfs_create_dir("error_injection", NULL);
+
+	file = debugfs_create_file("list", 0444, dir, NULL, &ei_fops);
+	if (IS_ERR(file)) {
+		debugfs_remove(dir);
+		return PTR_ERR(file);
+	}
+
+	return 0;
+}
+
+static int __init init_error_injection(void)
+{
+	populate_kernel_ei_list();
+
+	if (!module_ei_init())
+		ei_debugfs_init();
+
+	return 0;
+}
+late_initcall(init_error_injection);