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, 74 insertions, 0 deletions

diff --git a/Documentation/driver-api/pm/notifiers.rst b/Documentation/driver-api/pm/notifiers.rst
new file mode 100644
index 000000000..186435c43
--- /dev/null
+++ b/Documentation/driver-api/pm/notifiers.rst
@@ -0,0 +1,74 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+=============================
+Suspend/Hibernation Notifiers
+=============================
+
+:Copyright: |copy| 2016 Intel Corporation
+
+:Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
+
+
+There are some operations that subsystems or drivers may want to carry out
+before hibernation/suspend or after restore/resume, but they require the system
+to be fully functional, so the drivers' and subsystems' ``->suspend()`` and
+``->resume()`` or even ``->prepare()`` and ``->complete()`` callbacks are not
+suitable for this purpose.
+
+For example, device drivers may want to upload firmware to their devices after
+resume/restore, but they cannot do it by calling :c:func:`request_firmware()`
+from their ``->resume()`` or ``->complete()`` callback routines (user land
+processes are frozen at these points).  The solution may be to load the firmware
+into memory before processes are frozen and upload it from there in the
+``->resume()`` routine.  A suspend/hibernation notifier may be used for that.
+
+Subsystems or drivers having such needs can register suspend notifiers that
+will be called upon the following events by the PM core:
+
+``PM_HIBERNATION_PREPARE``
+	The system is going to hibernate, tasks will be frozen immediately. This
+	is different from ``PM_SUSPEND_PREPARE`` below,	because in this case
+	additional work is done between the notifiers and the invocation of PM
+	callbacks for the "freeze" transition.
+
+``PM_POST_HIBERNATION``
+	The system memory state has been restored from a hibernation image or an
+	error occurred during hibernation.  Device restore callbacks have been
+	executed and tasks have been thawed.
+
+``PM_RESTORE_PREPARE``
+	The system is going to restore a hibernation image.  If all goes well,
+	the restored image kernel will issue a ``PM_POST_HIBERNATION``
+	notification.
+
+``PM_POST_RESTORE``
+	An error occurred during restore from hibernation.  Device restore
+	callbacks have been executed and tasks have been thawed.
+
+``PM_SUSPEND_PREPARE``
+	The system is preparing for suspend.
+
+``PM_POST_SUSPEND``
+	The system has just resumed or an error occurred during suspend.  Device
+	resume callbacks have been executed and tasks have been thawed.
+
+It is generally assumed that whatever the notifiers do for
+``PM_HIBERNATION_PREPARE``, should be undone for ``PM_POST_HIBERNATION``.
+Analogously, operations carried out for ``PM_SUSPEND_PREPARE`` should be
+reversed for ``PM_POST_SUSPEND``.
+
+Moreover, if one of the notifiers fails for the ``PM_HIBERNATION_PREPARE`` or
+``PM_SUSPEND_PREPARE`` event, the notifiers that have already succeeded for that
+event will be called for ``PM_POST_HIBERNATION`` or ``PM_POST_SUSPEND``,
+respectively.
+
+The hibernation and suspend notifiers are called with :c:data:`pm_mutex` held.
+They are defined in the usual way, but their last argument is meaningless (it is
+always NULL).
+
+To register and/or unregister a suspend notifier use
+:c:func:`register_pm_notifier()` and :c:func:`unregister_pm_notifier()`,
+respectively (both defined in :file:`include/linux/suspend.h`).  If you don't
+need to unregister the notifier, you can also use the :c:func:`pm_notifier()`
+macro defined in :file:`include/linux/suspend.h`.