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, 266 insertions, 0 deletions

diff --git a/arch/alpha/mm/init.c b/arch/alpha/mm/init.c
new file mode 100644
index 000000000..f4d65a60c
--- /dev/null
+++ b/arch/alpha/mm/init.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  linux/arch/alpha/mm/init.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ */
+
+/* 2.3.x zone allocator, 1999 Andrea Arcangeli <andrea@suse.de> */
+
+#include <linux/pagemap.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/init.h>
+#include <linux/memblock.h> /* max_low_pfn */
+#include <linux/vmalloc.h>
+#include <linux/gfp.h>
+
+#include <linux/uaccess.h>
+#include <asm/pgalloc.h>
+#include <asm/hwrpb.h>
+#include <asm/dma.h>
+#include <asm/mmu_context.h>
+#include <asm/console.h>
+#include <asm/tlb.h>
+#include <asm/setup.h>
+#include <asm/sections.h>
+
+#include "../kernel/proto.h"
+
+static struct pcb_struct original_pcb;
+
+pgd_t *
+pgd_alloc(struct mm_struct *mm)
+{
+	pgd_t *ret, *init;
+
+	ret = __pgd_alloc(mm, 0);
+	init = pgd_offset(&init_mm, 0UL);
+	if (ret) {
+#ifdef CONFIG_ALPHA_LARGE_VMALLOC
+		memcpy (ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
+			(PTRS_PER_PGD - USER_PTRS_PER_PGD - 1)*sizeof(pgd_t));
+#else
+		pgd_val(ret[PTRS_PER_PGD-2]) = pgd_val(init[PTRS_PER_PGD-2]);
+#endif
+
+		/* The last PGD entry is the VPTB self-map.  */
+		pgd_val(ret[PTRS_PER_PGD-1])
+		  = pte_val(mk_pte(virt_to_page(ret), PAGE_KERNEL));
+	}
+	return ret;
+}
+
+
+static inline unsigned long
+load_PCB(struct pcb_struct *pcb)
+{
+	pcb->ksp = (unsigned long)current_stack_pointer;
+	return __reload_thread(pcb);
+}
+
+/* Set up initial PCB, VPTB, and other such nicities.  */
+
+static inline void
+switch_to_system_map(void)
+{
+	unsigned long newptbr;
+	unsigned long original_pcb_ptr;
+
+	/* Initialize the kernel's page tables.  Linux puts the vptb in
+	   the last slot of the L1 page table.  */
+	memset(swapper_pg_dir, 0, PAGE_SIZE);
+	newptbr = ((unsigned long) swapper_pg_dir - PAGE_OFFSET) >> PAGE_SHIFT;
+	pgd_val(swapper_pg_dir[1023]) =
+		(newptbr << 32) | pgprot_val(PAGE_KERNEL);
+
+	/* Set the vptb.  This is often done by the bootloader, but 
+	   shouldn't be required.  */
+	if (hwrpb->vptb != 0xfffffffe00000000UL) {
+		wrvptptr(0xfffffffe00000000UL);
+		hwrpb->vptb = 0xfffffffe00000000UL;
+		hwrpb_update_checksum(hwrpb);
+	}
+
+	/* Also set up the real kernel PCB while we're at it.  */
+	init_thread_info.pcb.ptbr = newptbr;
+	init_thread_info.pcb.flags = 1;	/* set FEN, clear everything else */
+	original_pcb_ptr = load_PCB(&init_thread_info.pcb);
+	tbia();
+
+	/* Save off the contents of the original PCB so that we can
+	   restore the original console's page tables for a clean reboot.
+
+	   Note that the PCB is supposed to be a physical address, but
+	   since KSEG values also happen to work, folks get confused.
+	   Check this here.  */
+
+	if (original_pcb_ptr < PAGE_OFFSET) {
+		original_pcb_ptr = (unsigned long)
+			phys_to_virt(original_pcb_ptr);
+	}
+	original_pcb = *(struct pcb_struct *) original_pcb_ptr;
+}
+
+int callback_init_done;
+
+void * __init
+callback_init(void * kernel_end)
+{
+	struct crb_struct * crb;
+	pgd_t *pgd;
+	p4d_t *p4d;
+	pud_t *pud;
+	pmd_t *pmd;
+	void *two_pages;
+
+	/* Starting at the HWRPB, locate the CRB. */
+	crb = (struct crb_struct *)((char *)hwrpb + hwrpb->crb_offset);
+
+	if (alpha_using_srm) {
+		/* Tell the console whither it is to be remapped. */
+		if (srm_fixup(VMALLOC_START, (unsigned long)hwrpb))
+			__halt();		/* "We're boned."  --Bender */
+
+		/* Edit the procedure descriptors for DISPATCH and FIXUP. */
+		crb->dispatch_va = (struct procdesc_struct *)
+			(VMALLOC_START + (unsigned long)crb->dispatch_va
+			 - crb->map[0].va);
+		crb->fixup_va = (struct procdesc_struct *)
+			(VMALLOC_START + (unsigned long)crb->fixup_va
+			 - crb->map[0].va);
+	}
+
+	switch_to_system_map();
+
+	/* Allocate one PGD and one PMD.  In the case of SRM, we'll need
+	   these to actually remap the console.  There is an assumption
+	   here that only one of each is needed, and this allows for 8MB.
+	   On systems with larger consoles, additional pages will be
+	   allocated as needed during the mapping process.
+
+	   In the case of not SRM, but not CONFIG_ALPHA_LARGE_VMALLOC,
+	   we need to allocate the PGD we use for vmalloc before we start
+	   forking other tasks.  */
+
+	two_pages = (void *)
+	  (((unsigned long)kernel_end + ~PAGE_MASK) & PAGE_MASK);
+	kernel_end = two_pages + 2*PAGE_SIZE;
+	memset(two_pages, 0, 2*PAGE_SIZE);
+
+	pgd = pgd_offset_k(VMALLOC_START);
+	p4d = p4d_offset(pgd, VMALLOC_START);
+	pud = pud_offset(p4d, VMALLOC_START);
+	pud_set(pud, (pmd_t *)two_pages);
+	pmd = pmd_offset(pud, VMALLOC_START);
+	pmd_set(pmd, (pte_t *)(two_pages + PAGE_SIZE));
+
+	if (alpha_using_srm) {
+		static struct vm_struct console_remap_vm;
+		unsigned long nr_pages = 0;
+		unsigned long vaddr;
+		unsigned long i, j;
+
+		/* calculate needed size */
+		for (i = 0; i < crb->map_entries; ++i)
+			nr_pages += crb->map[i].count;
+
+		/* register the vm area */
+		console_remap_vm.flags = VM_ALLOC;
+		console_remap_vm.size = nr_pages << PAGE_SHIFT;
+		vm_area_register_early(&console_remap_vm, PAGE_SIZE);
+
+		vaddr = (unsigned long)console_remap_vm.addr;
+
+		/* Set up the third level PTEs and update the virtual
+		   addresses of the CRB entries.  */
+		for (i = 0; i < crb->map_entries; ++i) {
+			unsigned long pfn = crb->map[i].pa >> PAGE_SHIFT;
+			crb->map[i].va = vaddr;
+			for (j = 0; j < crb->map[i].count; ++j) {
+				/* Newer consoles (especially on larger
+				   systems) may require more pages of
+				   PTEs. Grab additional pages as needed. */
+				if (pmd != pmd_offset(pud, vaddr)) {
+					memset(kernel_end, 0, PAGE_SIZE);
+					pmd = pmd_offset(pud, vaddr);
+					pmd_set(pmd, (pte_t *)kernel_end);
+					kernel_end += PAGE_SIZE;
+				}
+				set_pte(pte_offset_kernel(pmd, vaddr),
+					pfn_pte(pfn, PAGE_KERNEL));
+				pfn++;
+				vaddr += PAGE_SIZE;
+			}
+		}
+	}
+
+	callback_init_done = 1;
+	return kernel_end;
+}
+
+void __init arch_zone_limits_init(unsigned long *max_zone_pfn)
+{
+	unsigned long dma_pfn;
+
+	dma_pfn = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
+	max_pfn = max_low_pfn;
+
+	max_zone_pfn[ZONE_DMA] = dma_pfn;
+	max_zone_pfn[ZONE_NORMAL] = max_pfn;
+}
+
+/*
+ * paging_init() initializes the kernel's ZERO_PGE.
+ */
+void __init paging_init(void)
+{
+	memset(absolute_pointer(ZERO_PGE), 0, PAGE_SIZE);
+}
+
+#if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM)
+void
+srm_paging_stop (void)
+{
+	/* Move the vptb back to where the SRM console expects it.  */
+	swapper_pg_dir[1] = swapper_pg_dir[1023];
+	tbia();
+	wrvptptr(0x200000000UL);
+	hwrpb->vptb = 0x200000000UL;
+	hwrpb_update_checksum(hwrpb);
+
+	/* Reload the page tables that the console had in use.  */
+	load_PCB(&original_pcb);
+	tbia();
+}
+#endif
+
+static const pgprot_t protection_map[16] = {
+	[VM_NONE]					= _PAGE_P(_PAGE_FOE | _PAGE_FOW |
+								  _PAGE_FOR),
+	[VM_READ]					= _PAGE_P(_PAGE_FOE | _PAGE_FOW),
+	[VM_WRITE]					= _PAGE_P(_PAGE_FOE),
+	[VM_WRITE | VM_READ]				= _PAGE_P(_PAGE_FOE),
+	[VM_EXEC]					= _PAGE_P(_PAGE_FOW | _PAGE_FOR),
+	[VM_EXEC | VM_READ]				= _PAGE_P(_PAGE_FOW),
+	[VM_EXEC | VM_WRITE]				= _PAGE_P(0),
+	[VM_EXEC | VM_WRITE | VM_READ]			= _PAGE_P(0),
+	[VM_SHARED]					= _PAGE_S(_PAGE_FOE | _PAGE_FOW |
+								  _PAGE_FOR),
+	[VM_SHARED | VM_READ]				= _PAGE_S(_PAGE_FOE | _PAGE_FOW),
+	[VM_SHARED | VM_WRITE]				= _PAGE_S(_PAGE_FOE),
+	[VM_SHARED | VM_WRITE | VM_READ]		= _PAGE_S(_PAGE_FOE),
+	[VM_SHARED | VM_EXEC]				= _PAGE_S(_PAGE_FOW | _PAGE_FOR),
+	[VM_SHARED | VM_EXEC | VM_READ]			= _PAGE_S(_PAGE_FOW),
+	[VM_SHARED | VM_EXEC | VM_WRITE]		= _PAGE_S(0),
+	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= _PAGE_S(0)
+};
+DECLARE_VM_GET_PAGE_PROT