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, 124 insertions, 0 deletions

diff --git a/arch/alpha/boot/head.S b/arch/alpha/boot/head.S
new file mode 100644
index 000000000..06a7c95fe
--- /dev/null
+++ b/arch/alpha/boot/head.S
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/alpha/boot/head.S
+ *
+ * initial bootloader stuff..
+ */
+
+#include <asm/pal.h>
+
+	.set noreorder
+	.globl	__start
+	.ent	__start
+__start:
+	br	$29,2f
+2:	ldgp	$29,0($29)
+	jsr	$26,start_kernel
+	call_pal PAL_halt
+	.end __start
+
+	.align 5
+	.globl	wrent
+	.ent	wrent
+wrent:
+	.prologue 0
+	call_pal PAL_wrent
+	ret ($26)
+	.end wrent
+
+	.align 5
+	.globl	wrkgp
+	.ent	wrkgp
+wrkgp:
+	.prologue 0
+	call_pal PAL_wrkgp
+	ret ($26)
+	.end wrkgp
+
+	.align 5
+	.globl	switch_to_osf_pal
+	.ent	switch_to_osf_pal
+switch_to_osf_pal:
+	subq	$30,128,$30
+	.frame	$30,128,$26
+	stq	$26,0($30)
+	stq	$1,8($30)
+	stq	$2,16($30)
+	stq	$3,24($30)
+	stq	$4,32($30)
+	stq	$5,40($30)
+	stq	$6,48($30)
+	stq	$7,56($30)
+	stq	$8,64($30)
+	stq	$9,72($30)
+	stq	$10,80($30)
+	stq	$11,88($30)
+	stq	$12,96($30)
+	stq	$13,104($30)
+	stq	$14,112($30)
+	stq	$15,120($30)
+	.prologue 0
+
+	stq	$30,0($17)	/* save KSP in PCB */
+
+	bis	$30,$30,$20	/* a4 = KSP */
+	br	$17,1f
+
+	ldq	$26,0($30)
+	ldq	$1,8($30)
+	ldq	$2,16($30)
+	ldq	$3,24($30)
+	ldq	$4,32($30)
+	ldq	$5,40($30)
+	ldq	$6,48($30)
+	ldq	$7,56($30)
+	ldq	$8,64($30)
+	ldq	$9,72($30)
+	ldq	$10,80($30)
+	ldq	$11,88($30)
+	ldq	$12,96($30)
+	ldq	$13,104($30)
+	ldq	$14,112($30)
+	ldq	$15,120($30)
+	addq	$30,128,$30
+	ret ($26)
+1:	call_pal PAL_swppal
+	.end	switch_to_osf_pal
+
+	.align 3
+	.globl	tbi
+	.ent	tbi
+tbi:
+	.prologue 0
+	call_pal PAL_tbi
+	ret	($26)
+	.end tbi
+
+	.align 3
+	.globl	halt
+	.ent	halt
+halt:
+	.prologue 0
+	call_pal PAL_halt
+	.end halt
+
+/* $16 - new stack page */
+	.align 3
+	.globl	move_stack
+	.ent	move_stack
+move_stack:
+	.prologue 0
+	lda	$0, 0x1fff($31)
+	and	$0, $30, $1			/* Stack offset */
+	or	$1, $16, $16			/* New stack pointer */
+	mov	$30, $1
+	mov	$16, $2
+1:	ldq	$3, 0($1)			/* Move the stack */
+	addq	$1, 8, $1
+	stq	$3, 0($2)
+	and	$0, $1, $4
+	addq	$2, 8, $2
+	bne	$4, 1b
+	mov	$16, $30
+	ret	($26)
+	.end move_stack