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, 104 insertions, 0 deletions

diff --git a/Documentation/input/userio.rst b/Documentation/input/userio.rst
new file mode 100644
index 000000000..7aaaa629b
--- /dev/null
+++ b/Documentation/input/userio.rst
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+.. include:: <isonum.txt>
+
+===================
+The userio Protocol
+===================
+
+
+:Copyright: |copy| 2015 Lyude Paul <thatslyude@gmail.com>
+
+Sponsored by Red Hat
+
+
+Introduction
+=============
+
+This module is intended to try to make the lives of input driver developers
+easier by allowing them to test various serio devices (mainly the various
+touchpads found on laptops) without having to have the physical device in front
+of them. userio accomplishes this by allowing any privileged userspace program
+to directly interact with the kernel's serio driver and control a virtual serio
+port from there.
+
+Usage overview
+==============
+
+In order to interact with the userio kernel module, one simply opens the
+/dev/userio character device in their applications. Commands are sent to the
+kernel module by writing to the device, and any data received from the serio
+driver is read as-is from the /dev/userio device. All of the structures and
+macros you need to interact with the device are defined in <linux/userio.h> and
+<linux/serio.h>.
+
+Command Structure
+=================
+
+The struct used for sending commands to /dev/userio is as follows::
+
+	struct userio_cmd {
+		__u8 type;
+		__u8 data;
+	};
+
+``type`` describes the type of command that is being sent. This can be any one
+of the USERIO_CMD macros defined in <linux/userio.h>. ``data`` is the argument
+that goes along with the command. In the event that the command doesn't have an
+argument, this field can be left untouched and will be ignored by the kernel.
+Each command should be sent by writing the struct directly to the character
+device. In the event that the command you send is invalid, an error will be
+returned by the character device and a more descriptive error will be printed
+to the kernel log. Only one command can be sent at a time, any additional data
+written to the character device after the initial command will be ignored.
+
+To close the virtual serio port, just close /dev/userio.
+
+Commands
+========
+
+USERIO_CMD_REGISTER
+~~~~~~~~~~~~~~~~~~~
+
+Registers the port with the serio driver and begins transmitting data back and
+forth. Registration can only be performed once a port type is set with
+USERIO_CMD_SET_PORT_TYPE. Has no argument.
+
+USERIO_CMD_SET_PORT_TYPE
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sets the type of port we're emulating, where ``data`` is the port type being
+set. Can be any of the serio type macros from <linux/serio.h>. For example:
+SERIO_8042 would set the port type to be a normal PS/2 port.
+
+USERIO_CMD_SET_PORT_PROTO
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sets the protocol of port we're emulating, where ``data`` is the protocol being
+set. Can be any of the serio proto macros from <linux/serio.h>. For example:
+SERIO_IFORCE would set the port type to be an I-Force serial joystick.
+
+USERIO_CMD_SET_PORT_ID
+~~~~~~~~~~~~~~~~~~~~~~
+
+Sets the ``id`` value on the identification of port we're emulating, where
+``data`` is the value being set.
+
+USERIO_CMD_SET_PORT_EXTRA
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sets the ``extra`` value on the identification of port we're emulating, where
+``data`` is the value being set.
+
+USERIO_CMD_SEND_INTERRUPT
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Sends an interrupt through the virtual serio port to the serio driver, where
+``data`` is the interrupt data being sent.
+
+Userspace tools
+===============
+
+The userio userspace tools are able to record PS/2 devices using some of the
+debugging information from i8042, and play back the devices on /dev/userio. The
+latest version of these tools can be found at:
+
+	https://github.com/Lyude/ps2emu