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) --- .../sched/membarrier-sync-core/arch-support.txt | 69 ++++++++++++++++++++++ .../features/sched/numa-balancing/arch-support.txt | 30 ++++++++++ 2 files changed, 99 insertions(+) create mode 100644 Documentation/features/sched/membarrier-sync-core/arch-support.txt create mode 100644 Documentation/features/sched/numa-balancing/arch-support.txt (limited to 'Documentation/features/sched') diff --git a/Documentation/features/sched/membarrier-sync-core/arch-support.txt b/Documentation/features/sched/membarrier-sync-core/arch-support.txt new file mode 100644 index 000000000..7425d2b99 --- /dev/null +++ b/Documentation/features/sched/membarrier-sync-core/arch-support.txt @@ -0,0 +1,69 @@ +# +# Feature name: membarrier-sync-core +# Kconfig: ARCH_HAS_MEMBARRIER_SYNC_CORE +# description: arch supports core serializing membarrier +# +# Architecture requirements +# +# * arm/arm64/powerpc/s390 +# +# Rely on implicit context synchronization as a result of exception return +# when returning from IPI handler, and when returning to user-space. +# +# * riscv +# +# riscv uses xRET as return from interrupt and to return to user-space. +# +# Given that xRET is not core serializing, we rely on FENCE.I for providing +# core serialization: +# +# - by calling sync_core_before_usermode() on return from interrupt (cf. +# ipi_sync_core()), +# +# - via switch_mm() and sync_core_before_usermode() (respectively, for +# uthread->uthread and kthread->uthread transitions) before returning +# to user-space. +# +# The serialization in switch_mm() is activated by prepare_sync_core_cmd(). +# +# * x86 +# +# x86-32 uses IRET as return from interrupt, which takes care of the IPI. +# However, it uses both IRET and SYSEXIT to go back to user-space. The IRET +# instruction is core serializing, but not SYSEXIT. +# +# x86-64 uses IRET as return from interrupt, which takes care of the IPI. +# However, it can return to user-space through either SYSRETL (compat code), +# SYSRETQ, or IRET. +# +# Given that neither SYSRET{L,Q}, nor SYSEXIT, are core serializing, we rely +# instead on write_cr3() performed by switch_mm() to provide core serialization +# after changing the current mm, and deal with the special case of kthread -> +# uthread (temporarily keeping current mm into active_mm) by issuing a +# sync_core_before_usermode() in that specific case. +# + ----------------------- + | arch |status| + ----------------------- + | alpha: | TODO | + | arc: | TODO | + | arm: | ok | + | arm64: | ok | + | csky: | TODO | + | hexagon: | TODO | + | loongarch: | TODO | + | m68k: | TODO | + | microblaze: | TODO | + | mips: | TODO | + | nios2: | TODO | + | openrisc: | TODO | + | parisc: | TODO | + | powerpc: | ok | + | riscv: | ok | + | s390: | ok | + | sh: | TODO | + | sparc: | TODO | + | um: | TODO | + | x86: | ok | + | xtensa: | TODO | + ----------------------- diff --git a/Documentation/features/sched/numa-balancing/arch-support.txt b/Documentation/features/sched/numa-balancing/arch-support.txt new file mode 100644 index 000000000..984601c7c --- /dev/null +++ b/Documentation/features/sched/numa-balancing/arch-support.txt @@ -0,0 +1,30 @@ +# +# Feature name: numa-balancing +# Kconfig: ARCH_SUPPORTS_NUMA_BALANCING +# description: arch supports NUMA balancing +# + ----------------------- + | arch |status| + ----------------------- + | alpha: | TODO | + | arc: | .. | + | arm: | .. | + | arm64: | ok | + | csky: | .. | + | hexagon: | .. | + | loongarch: | ok | + | m68k: | .. | + | microblaze: | .. | + | mips: | TODO | + | nios2: | .. | + | openrisc: | .. | + | parisc: | .. | + | powerpc: | ok | + | riscv: | ok | + | s390: | ok | + | sh: | .. | + | sparc: | TODO | + | um: | .. | + | x86: | ok | + | xtensa: | .. | + ----------------------- -- cgit v1.3.1