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, 54 insertions, 0 deletions

diff --git a/Documentation/admin-guide/device-mapper/delay.rst b/Documentation/admin-guide/device-mapper/delay.rst
new file mode 100644
index 000000000..a1e673c0e
--- /dev/null
+++ b/Documentation/admin-guide/device-mapper/delay.rst
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+========
+dm-delay
+========
+
+Device-Mapper's "delay" target delays reads and/or writes
+and/or flushes and optionally maps them to different devices.
+
+Arguments::
+
+    <device> <offset> <delay> [<write_device> <write_offset> <write_delay>
+			       [<flush_device> <flush_offset> <flush_delay>]]
+
+Table line has to either have 3, 6 or 9 arguments:
+
+3: apply offset and delay to read, write and flush operations on device
+
+6: apply offset and delay to device, also apply write_offset and write_delay
+   to write and flush operations on optionally different write_device with
+   optionally different sector offset
+
+9: same as 6 arguments plus define flush_offset and flush_delay explicitly
+   on/with optionally different flush_device/flush_offset.
+
+Offsets are specified in sectors.
+
+Delays are specified in milliseconds.
+
+
+Example scripts
+===============
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device named "delayed" delaying read, write and flush operations for 500ms.
+	#
+	dmsetup create delayed --table  "0 `blockdev --getsz $1` delay $1 0 500"
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device delaying write and flush operations for 400ms and
+	# splitting reads to device $1 but writes and flushes to different device $2
+	# to different offsets of 2048 and 4096 sectors respectively.
+	#
+	dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 2048 0 $2 4096 400"
+
+::
+	#!/bin/sh
+	#
+	# Create mapped device delaying reads for 50ms, writes for 100ms and flushes for 333ms
+	# onto the same backing device at offset 0 sectors.
+	#
+	dmsetup create delayed --table "0 `blockdev --getsz $1` delay $1 0 50 $2 0 100 $1 0 333"