drm/amd/display: use ARCH_HAS_KERNEL_FPU_SUPPORT

Now that all previously-supported architectures select
ARCH_HAS_KERNEL_FPU_SUPPORT, this code can depend on that symbol instead
of the existing list of architectures.  It can also take advantage of the
common kernel-mode FPU API and method of adjusting CFLAGS.

Link: https://lkml.kernel.org/r/20240329072441.591471-14-samuel.holland@sifive.com
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian König <christian.koenig@amd.com> 
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicolas Schier <nicolas@fjasle.eu>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: WANG Xuerui <git@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: SiFiveHolland

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 (X86 || LOONGARCH || (PPC64 && ALTIVEC) || (ARM64 && KERNEL_MODE_NEON && !CC_IS_CLANG))
+	select DRM_AMD_DC_FP if ARCH_HAS_KERNEL_FPU_SUPPORT && (!ARM64 || !CC_IS_CLANG)
 	help
 	  Choose this option if you want to use the new display engine
 	  support for AMDGPU. This adds required support for Vega and

drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c

@@ -26,16 +26,7 @@
 
 #include "dc_trace.h"
 
-#if defined(CONFIG_X86)
-#include <asm/fpu/api.h>
-#elif defined(CONFIG_PPC64)
-#include <asm/switch_to.h>
-#include <asm/cputable.h>
-#elif defined(CONFIG_ARM64)
-#include <asm/neon.h>
-#elif defined(CONFIG_LOONGARCH)
-#include <asm/fpu.h>
-#endif
+#include <linux/fpu.h>
 
 /**
  * DOC: DC FPU manipulation overview
@@ -87,16 +78,9 @@ void dc_fpu_begin(const char *function_name, const int line)
 	WARN_ON_ONCE(!in_task());
 	preempt_disable();
 	depth = __this_cpu_inc_return(fpu_recursion_depth);
-
 	if (depth == 1) {
-#if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
+		BUG_ON(!kernel_fpu_available());
 		kernel_fpu_begin();
-#elif defined(CONFIG_PPC64)
-		if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE))
-			enable_kernel_fp();
-#elif defined(CONFIG_ARM64)
-		kernel_neon_begin();
-#endif
 	}
 
 	TRACE_DCN_FPU(true, function_name, line, depth);
@@ -118,14 +102,7 @@ void dc_fpu_end(const char *function_name, const int line)
 
 	depth = __this_cpu_dec_return(fpu_recursion_depth);
 	if (depth == 0) {
-#if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
 		kernel_fpu_end();
-#elif defined(CONFIG_PPC64)
-		if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE))
-			disable_kernel_fp();
-#elif defined(CONFIG_ARM64)
-		kernel_neon_end();
-#endif
 	} else {
 		WARN_ON_ONCE(depth < 0);
 	}

drivers/gpu/drm/amd/display/dc/dml/Makefile

@@ -25,40 +25,8 @@
 # It provides the general basic services required by other DAL
 # subcomponents.
 
-ifdef CONFIG_X86
-dml_ccflags-$(CONFIG_CC_IS_GCC) := -mhard-float
-dml_ccflags := $(dml_ccflags-y) -msse
-endif
-
-ifdef CONFIG_PPC64
-dml_ccflags := -mhard-float
-endif
-
-ifdef CONFIG_ARM64
-dml_rcflags := -mgeneral-regs-only
-endif
-
-ifdef CONFIG_LOONGARCH
-dml_ccflags := -mfpu=64
-dml_rcflags := -msoft-float
-endif
-
-ifdef CONFIG_CC_IS_GCC
-ifneq ($(call gcc-min-version, 70100),y)
-IS_OLD_GCC = 1
-endif
-endif
-
-ifdef CONFIG_X86
-ifdef IS_OLD_GCC
-# Stack alignment mismatch, proceed with caution.
-# GCC < 7.1 cannot compile code using `double` and -mpreferred-stack-boundary=3
-# (8B stack alignment).
-dml_ccflags += -mpreferred-stack-boundary=4
-else
-dml_ccflags += -msse2
-endif
-endif
+dml_ccflags := $(CC_FLAGS_FPU)
+dml_rcflags := $(CC_FLAGS_NO_FPU)
 
 ifneq ($(CONFIG_FRAME_WARN),0)
 ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)),y)

drivers/gpu/drm/amd/display/dc/dml2/Makefile

@@ -24,40 +24,8 @@
 #
 # Makefile for dml2.
 
-ifdef CONFIG_X86
-dml2_ccflags-$(CONFIG_CC_IS_GCC) := -mhard-float
-dml2_ccflags := $(dml2_ccflags-y) -msse
-endif
-
-ifdef CONFIG_PPC64
-dml2_ccflags := -mhard-float
-endif
-
-ifdef CONFIG_ARM64
-dml2_rcflags := -mgeneral-regs-only
-endif
-
-ifdef CONFIG_LOONGARCH
-dml2_ccflags := -mfpu=64
-dml2_rcflags := -msoft-float
-endif
-
-ifdef CONFIG_CC_IS_GCC
-ifeq ($(call cc-ifversion, -lt, 0701, y), y)
-IS_OLD_GCC = 1
-endif
-endif
-
-ifdef CONFIG_X86
-ifdef IS_OLD_GCC
-# Stack alignment mismatch, proceed with caution.
-# GCC < 7.1 cannot compile code using `double` and -mpreferred-stack-boundary=3
-# (8B stack alignment).
-dml2_ccflags += -mpreferred-stack-boundary=4
-else
-dml2_ccflags += -msse2
-endif
-endif
+dml2_ccflags := $(CC_FLAGS_FPU)
+dml2_rcflags := $(CC_FLAGS_NO_FPU)
 
 ifneq ($(CONFIG_FRAME_WARN),0)
 ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)),y)