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, 137 insertions, 0 deletions

diff --git a/Documentation/sphinx/kernel_feat.py b/Documentation/sphinx/kernel_feat.py
new file mode 100644
index 000000000..bdc0fef5c
--- /dev/null
+++ b/Documentation/sphinx/kernel_feat.py
@@ -0,0 +1,137 @@
+# coding=utf-8
+# SPDX-License-Identifier: GPL-2.0
+#
+"""
+    kernel-feat
+    ~~~~~~~~~~~
+
+    Implementation of the ``kernel-feat`` reST-directive.
+
+    :copyright:  Copyright (C) 2016  Markus Heiser
+    :copyright:  Copyright (C) 2016-2019  Mauro Carvalho Chehab
+    :maintained-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
+    :license:    GPL Version 2, June 1991 see Linux/COPYING for details.
+
+    The ``kernel-feat`` (:py:class:`KernelFeat`) directive calls the
+    tools/docs/get_feat.pl script to parse the Kernel ABI files.
+
+    Overview of directive's argument and options.
+
+    .. code-block:: rst
+
+        .. kernel-feat:: <ABI directory location>
+            :debug:
+
+    The argument ``<ABI directory location>`` is required. It contains the
+    location of the ABI files to be parsed.
+
+    ``debug``
+      Inserts a code-block with the *raw* reST. Sometimes it is helpful to see
+      what reST is generated.
+
+"""
+
+import codecs
+import os
+import re
+import sys
+
+from docutils import nodes, statemachine
+from docutils.statemachine import ViewList
+from docutils.parsers.rst import directives, Directive
+from sphinx.util.docutils import switch_source_input
+
+srctree = os.path.abspath(os.environ["srctree"])
+sys.path.insert(0, os.path.join(srctree, "tools/lib/python"))
+
+from feat.parse_features import ParseFeature                # pylint: disable=C0413
+
+def ErrorString(exc):  # Shamelessly stolen from docutils
+    return f'{exc.__class__.__name}: {exc}'
+
+__version__  = '1.0'
+
+def setup(app):
+
+    app.add_directive("kernel-feat", KernelFeat)
+    return dict(
+        version = __version__
+        , parallel_read_safe = True
+        , parallel_write_safe = True
+    )
+
+class KernelFeat(Directive):
+
+    """KernelFeat (``kernel-feat``) directive"""
+
+    required_arguments = 1
+    optional_arguments = 2
+    has_content = False
+    final_argument_whitespace = True
+
+    option_spec = {
+        "debug"     : directives.flag
+    }
+
+    def warn(self, message, **replace):
+        replace["fname"]   = self.state.document.current_source
+        replace["line_no"] = replace.get("line_no", self.lineno)
+        message = ("%(fname)s:%(line_no)s: [kernel-feat WARN] : " + message) % replace
+        self.state.document.settings.env.app.warn(message, prefix="")
+
+    def run(self):
+        doc = self.state.document
+        if not doc.settings.file_insertion_enabled:
+            raise self.warning("docutils: file insertion disabled")
+
+        env = doc.settings.env
+
+        srctree = os.path.abspath(os.environ["srctree"])
+
+        feature_dir = os.path.join(srctree, 'Documentation', self.arguments[0])
+
+        feat = ParseFeature(feature_dir, False, True)
+        feat.parse()
+
+        if len(self.arguments) > 1:
+            arch = self.arguments[1]
+            lines = feat.output_arch_table(arch)
+        else:
+            lines = feat.output_matrix()
+
+        line_regex = re.compile(r"^\.\. FILE (\S+)$")
+
+        out_lines = ""
+
+        for line in lines.split("\n"):
+            match = line_regex.search(line)
+            if match:
+                fname = match.group(1)
+
+                # Add the file to Sphinx build dependencies
+                env.note_dependency(os.path.abspath(fname))
+            else:
+                out_lines += line + "\n"
+
+        nodeList = self.nestedParse(out_lines, self.arguments[0])
+        return nodeList
+
+    def nestedParse(self, lines, fname):
+        content = ViewList()
+        node    = nodes.section()
+
+        if "debug" in self.options:
+            code_block = "\n\n.. code-block:: rst\n    :linenos:\n"
+            for l in lines.split("\n"):
+                code_block += "\n    " + l
+            lines = code_block + "\n\n"
+
+        for c, l in enumerate(lines.split("\n")):
+            content.append(l, fname, c)
+
+        buf  = self.state.memo.title_styles, self.state.memo.section_level, self.state.memo.reporter
+
+        with switch_source_input(self.state, content):
+            self.state.nested_parse(content, 0, node, match_titles=1)
+
+        return node.children