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, 192 insertions, 0 deletions

diff --git a/Documentation/admin-guide/index.rst b/Documentation/admin-guide/index.rst
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+=================================================
+The Linux kernel user's and administrator's guide
+=================================================
+
+The following is a collection of user-oriented documents that have been
+added to the kernel over time.  There is, as yet, little overall order or
+organization here — this material was not written to be a single, coherent
+document!  With luck things will improve quickly over time.
+
+General guides to kernel administration
+---------------------------------------
+
+This initial section contains overall information, including the README
+file describing the kernel as a whole, documentation on kernel parameters,
+etc.
+
+.. toctree::
+   :maxdepth: 1
+
+   README
+   devices
+
+   features
+
+A big part of the kernel's administrative interface is the /proc and sysfs
+virtual filesystems; these documents describe how to interact with tem
+
+.. toctree::
+   :maxdepth: 1
+
+   sysfs-rules
+   sysctl/index
+   cputopology
+   abi
+
+Security-related documentation:
+
+.. toctree::
+   :maxdepth: 1
+
+   hw-vuln/index
+   LSM/index
+   perf-security
+
+Booting the kernel
+------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   bootconfig
+   kernel-parameters
+   efi-stub
+   initrd
+
+
+Tracking down and identifying problems
+--------------------------------------
+
+Here is a set of documents aimed at users who are trying to track down
+problems and bugs in particular.
+
+.. toctree::
+   :maxdepth: 1
+
+   reporting-issues
+   reporting-regressions
+   quickly-build-trimmed-linux
+   verify-bugs-and-bisect-regressions
+   bug-hunting
+   bug-bisect
+   tainted-kernels
+   ramoops
+   dynamic-debug-howto
+   init
+   kdump/index
+   perf/index
+   pstore-blk
+   clearing-warn-once
+   kernel-per-CPU-kthreads
+   lockup-watchdogs
+   RAS/index
+   sysrq
+
+
+Core-kernel subsystems
+----------------------
+
+These documents describe core-kernel administration interfaces that are
+likely to be of interest on almost any system.
+
+.. toctree::
+   :maxdepth: 1
+
+   cgroup-v2
+   cgroup-v1/index
+   cpu-isolation
+   cpu-load
+   mm/index
+   module-signing
+   namespaces/index
+   numastat
+   pm/index
+   syscall-user-dispatch
+
+Support for non-native binary formats.  Note that some of these
+documents are ... old ...
+
+.. toctree::
+   :maxdepth: 1
+
+   binfmt-misc
+   java
+   mono
+
+
+Block-layer and filesystem administration
+-----------------------------------------
+
+.. toctree::
+   :maxdepth: 1
+
+   bcache
+   binderfs
+   blockdev/index
+   cifs/index
+   device-mapper/index
+   ext4
+   filesystem-monitoring
+   nfs/index
+   iostats
+   jfs
+   md
+   ufs
+   xfs
+
+Device-specific guides
+----------------------
+
+How to configure your hardware within your Linux system.
+
+.. toctree::
+   :maxdepth: 1
+
+   acpi/index
+   aoe/index
+   auxdisplay/index
+   braille-console
+   btmrvl
+   dell_rbu
+   edid
+   gpio/index
+   hw_random
+   laptops/index
+   lcd-panel-cgram
+   media/index
+   nvme-multipath
+   parport
+   pnp
+   rapidio
+   rtc
+   serial-console
+   svga
+   thermal/index
+   thunderbolt
+   vga-softcursor
+   video-output
+
+Workload analysis
+-----------------
+
+This is the beginning of a section with information of interest to
+application developers and system integrators doing analysis of the
+Linux kernel for safety critical applications. Documents supporting
+analysis of kernel interactions with applications, and key kernel
+subsystems expectations will be found here.
+
+.. toctree::
+   :maxdepth: 1
+
+   workload-tracing
+
+Everything else
+---------------
+
+A few hard-to-categorize and generally obsolete documents.
+
+.. toctree::
+   :maxdepth: 1
+
+   ldm
+   unicode