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, 103 insertions, 0 deletions

diff --git a/Documentation/PCI/endpoint/pci-test-function.rst b/Documentation/PCI/endpoint/pci-test-function.rst
new file mode 100644
index 000000000..3c8521d7a
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-test-function.rst
@@ -0,0 +1,103 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+PCI Test Function
+=================
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+Traditionally PCI RC has always been validated by using standard
+PCI cards like ethernet PCI cards or USB PCI cards or SATA PCI cards.
+However with the addition of EP-core in linux kernel, it is possible
+to configure a PCI controller that can operate in EP mode to work as
+a test device.
+
+The PCI endpoint test device is a virtual device (defined in software)
+used to test the endpoint functionality and serve as a sample driver
+for other PCI endpoint devices (to use the EP framework).
+
+The PCI endpoint test device has the following registers:
+
+	1) PCI_ENDPOINT_TEST_MAGIC
+	2) PCI_ENDPOINT_TEST_COMMAND
+	3) PCI_ENDPOINT_TEST_STATUS
+	4) PCI_ENDPOINT_TEST_SRC_ADDR
+	5) PCI_ENDPOINT_TEST_DST_ADDR
+	6) PCI_ENDPOINT_TEST_SIZE
+	7) PCI_ENDPOINT_TEST_CHECKSUM
+	8) PCI_ENDPOINT_TEST_IRQ_TYPE
+	9) PCI_ENDPOINT_TEST_IRQ_NUMBER
+
+* PCI_ENDPOINT_TEST_MAGIC
+
+This register will be used to test BAR0. A known pattern will be written
+and read back from MAGIC register to verify BAR0.
+
+* PCI_ENDPOINT_TEST_COMMAND
+
+This register will be used by the host driver to indicate the function
+that the endpoint device must perform.
+
+========	================================================================
+Bitfield	Description
+========	================================================================
+Bit 0		raise legacy IRQ
+Bit 1		raise MSI IRQ
+Bit 2		raise MSI-X IRQ
+Bit 3		read command (read data from RC buffer)
+Bit 4		write command (write data to RC buffer)
+Bit 5		copy command (copy data from one RC buffer to another RC buffer)
+========	================================================================
+
+* PCI_ENDPOINT_TEST_STATUS
+
+This register reflects the status of the PCI endpoint device.
+
+========	==============================
+Bitfield	Description
+========	==============================
+Bit 0		read success
+Bit 1		read fail
+Bit 2		write success
+Bit 3		write fail
+Bit 4		copy success
+Bit 5		copy fail
+Bit 6		IRQ raised
+Bit 7		source address is invalid
+Bit 8		destination address is invalid
+========	==============================
+
+* PCI_ENDPOINT_TEST_SRC_ADDR
+
+This register contains the source address (RC buffer address) for the
+COPY/READ command.
+
+* PCI_ENDPOINT_TEST_DST_ADDR
+
+This register contains the destination address (RC buffer address) for
+the COPY/WRITE command.
+
+* PCI_ENDPOINT_TEST_IRQ_TYPE
+
+This register contains the interrupt type (Legacy/MSI) triggered
+for the READ/WRITE/COPY and raise IRQ (Legacy/MSI) commands.
+
+Possible types:
+
+======	==
+Legacy	0
+MSI	1
+MSI-X	2
+======	==
+
+* PCI_ENDPOINT_TEST_IRQ_NUMBER
+
+This register contains the triggered ID interrupt.
+
+Admissible values:
+
+======	===========
+Legacy	0
+MSI	[1 .. 32]
+MSI-X	[1 .. 2048]
+======	===========