From 106b4a2a78b2a2f14885604891957b84bba502db Mon Sep 17 00:00:00 2001 From: Adrian Betschart Date: Fri, 11 Sep 2026 17:13:14 +0200 Subject: drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validation 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 Assisted-by: Claude Code:claude-fable-5-1 Signed-off-by: Adrian Betschart Reviewed-by: Fangzhi Zuo Tested-by: Adolfo Rodrigues Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher (cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7) --- include/asm-generic/cmpxchg-local.h | 68 +++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 include/asm-generic/cmpxchg-local.h (limited to 'include/asm-generic/cmpxchg-local.h') diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h new file mode 100644 index 000000000..f27d66fdc --- /dev/null +++ b/include/asm-generic/cmpxchg-local.h @@ -0,0 +1,68 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H +#define __ASM_GENERIC_CMPXCHG_LOCAL_H + +#include +#include + +extern unsigned long wrong_size_cmpxchg(volatile void *ptr) + __noreturn; + +/* + * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned + * long parameter, supporting various types of architectures. + */ +static inline unsigned long __generic_cmpxchg_local(volatile void *ptr, + unsigned long old, unsigned long new, int size) +{ + unsigned long flags, prev; + + /* + * Sanity checking, compile-time. + */ + if (size == 8 && sizeof(unsigned long) != 8) + wrong_size_cmpxchg(ptr); + + raw_local_irq_save(flags); + switch (size) { + case 1: prev = *(u8 *)ptr; + if (prev == (old & 0xffu)) + *(u8 *)ptr = (new & 0xffu); + break; + case 2: prev = *(u16 *)ptr; + if (prev == (old & 0xffffu)) + *(u16 *)ptr = (new & 0xffffu); + break; + case 4: prev = *(u32 *)ptr; + if (prev == (old & 0xffffffffu)) + *(u32 *)ptr = (new & 0xffffffffu); + break; + case 8: prev = *(u64 *)ptr; + if (prev == old) + *(u64 *)ptr = (u64)new; + break; + default: + wrong_size_cmpxchg(ptr); + } + raw_local_irq_restore(flags); + return prev; +} + +/* + * Generic version of __cmpxchg64_local. Takes an u64 parameter. + */ +static inline u64 __generic_cmpxchg64_local(volatile void *ptr, + u64 old, u64 new) +{ + u64 prev; + unsigned long flags; + + raw_local_irq_save(flags); + prev = *(u64 *)ptr; + if (prev == old) + *(u64 *)ptr = new; + raw_local_irq_restore(flags); + return prev; +} + +#endif -- cgit v1.3.1