From 301daa346f0e34a87fb6c1e4a05db2aa0a66b573 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Fri, 14 Jun 2024 12:54:52 -0700 Subject: [PATCH] drm/amd/display: Disable CONFIG_DRM_AMD_DC_FP for RISC-V with clang Commit 77acc6b55ae4 ("riscv: add support for kernel-mode FPU") and commit a28e4b672f04 ("drm/amd/display: use ARCH_HAS_KERNEL_FPU_SUPPORT") enabled support for CONFIG_DRM_AMD_DC_FP with RISC-V. Unfortunately, this exposed -Wframe-larger-than warnings (which become fatal with CONFIG_WERROR=y) when building ARCH=riscv allmodconfig with clang: drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:58:13: error: stack frame size (2448) exceeds limit (2048) in 'DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerformanceCalculation' [-Werror,-Wframe-larger-than] 58 | static void DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerformanceCalculation( | ^ 1 error generated. Many functions in this file use a large number of parameters, which must be passed on the stack at a certain pointer due to register exhaustion, which can cause high stack usage when inlining and issues with stack slot analysis get involved. While the compiler can and should do better (as GCC uses less than half the amount of stack space for the same function), it is not as simple as a fix as adjusting the functions not to take a large number of parameters. Unfortunately, modifying these files to avoid the problem is a difficult to justify approach because any revisions to the files in the kernel tree never make it back to the original source (so copies of the code for newer hardware revisions just reintroduce the issue) and the files are hard to read/modify due to being "gcc-parsable HW gospel, coming straight from HW engineers". Avoid building the problematic code for RISC-V by modifying the existing condition for arm64 that exists for the same reason. Factor out the logical not to make the condition a little more readable naturally. Fixes: a28e4b672f04 ("drm/amd/display: use ARCH_HAS_KERNEL_FPU_SUPPORT") Reported-by: Palmer Dabbelt Closes: https://lore.kernel.org/20240530145741.7506-2-palmer@rivosinc.com/ Reviewed-by: Harry Wentland Signed-off-by: Nathan Chancellor Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig index 5fcd4f778dc3..47b8b49da8a7 100644 --- a/drivers/gpu/drm/amd/display/Kconfig +++ b/drivers/gpu/drm/amd/display/Kconfig @@ -8,7 +8,7 @@ config DRM_AMD_DC depends on BROKEN || !CC_IS_CLANG || ARM64 || RISCV || SPARC64 || X86_64 select SND_HDA_COMPONENT if SND_HDA_CORE # !CC_IS_CLANG: https://github.com/ClangBuiltLinux/linux/issues/1752 - select DRM_AMD_DC_FP if ARCH_HAS_KERNEL_FPU_SUPPORT && (!ARM64 || !CC_IS_CLANG) + select DRM_AMD_DC_FP if ARCH_HAS_KERNEL_FPU_SUPPORT && !(CC_IS_CLANG && (ARM64 || RISCV)) help Choose this option if you want to use the new display engine support for AMDGPU. This adds required support for Vega and