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, 88 insertions, 0 deletions

diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c
new file mode 100644
index 000000000..0f0f2d851
--- /dev/null
+++ b/arch/powerpc/lib/pmem.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright(c) 2017 IBM Corporation. All rights reserved.
+ */
+
+#include <linux/string.h>
+#include <linux/export.h>
+#include <linux/uaccess.h>
+#include <linux/libnvdimm.h>
+
+#include <asm/cacheflush.h>
+
+static inline void __clean_pmem_range(unsigned long start, unsigned long stop)
+{
+	unsigned long shift = l1_dcache_shift();
+	unsigned long bytes = l1_dcache_bytes();
+	void *addr = (void *)(start & ~(bytes - 1));
+	unsigned long size = stop - (unsigned long)addr + (bytes - 1);
+	unsigned long i;
+
+	for (i = 0; i < size >> shift; i++, addr += bytes)
+		asm volatile(PPC_DCBSTPS(%0, %1): :"i"(0), "r"(addr): "memory");
+}
+
+static inline void __flush_pmem_range(unsigned long start, unsigned long stop)
+{
+	unsigned long shift = l1_dcache_shift();
+	unsigned long bytes = l1_dcache_bytes();
+	void *addr = (void *)(start & ~(bytes - 1));
+	unsigned long size = stop - (unsigned long)addr + (bytes - 1);
+	unsigned long i;
+
+	for (i = 0; i < size >> shift; i++, addr += bytes)
+		asm volatile(PPC_DCBFPS(%0, %1): :"i"(0), "r"(addr): "memory");
+}
+
+static inline void clean_pmem_range(unsigned long start, unsigned long stop)
+{
+	if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		return __clean_pmem_range(start, stop);
+}
+
+static inline void flush_pmem_range(unsigned long start, unsigned long stop)
+{
+	if (cpu_has_feature(CPU_FTR_ARCH_207S))
+		return __flush_pmem_range(start, stop);
+}
+
+/*
+ * CONFIG_ARCH_HAS_PMEM_API symbols
+ */
+void arch_wb_cache_pmem(void *addr, size_t size)
+{
+	unsigned long start = (unsigned long) addr;
+	clean_pmem_range(start, start + size);
+}
+EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
+
+void arch_invalidate_pmem(void *addr, size_t size)
+{
+	unsigned long start = (unsigned long) addr;
+	flush_pmem_range(start, start + size);
+}
+EXPORT_SYMBOL_GPL(arch_invalidate_pmem);
+
+/*
+ * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols
+ */
+size_t copy_from_user_flushcache(void *dest, const void __user *src,
+				 size_t size)
+{
+	unsigned long not_copied, start = (unsigned long) dest;
+
+	src = mask_user_address(src);
+	not_copied = __copy_from_user(dest, src, size);
+	clean_pmem_range(start, start + size);
+
+	return not_copied;
+}
+
+void memcpy_flushcache(void *dest, const void *src, size_t size)
+{
+	unsigned long start = (unsigned long) dest;
+
+	memcpy(dest, src, size);
+	clean_pmem_range(start, start + size);
+}
+EXPORT_SYMBOL(memcpy_flushcache);