drm/amd/display: Allow building DC with clang on LoongArch

Clang on LoongArch (18+) appears to be unaffected by the bug causing
excessive stack usage in calculate_bandwidth(). But when building DC_FP
support the stack frame size can be as large as 2816 bytes, which causes
the FRAME_WARN build warnings. So on LoongArch we allow building DC with
clang, but disable DC_FP by default.

The help message is also updated.

Tested-by: Rui Wang <[email protected]>
Signed-off-by: Huacai Chen <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>

Author: chenhuacai

drivers/gpu/drm/amd/display/Kconfig

@@ -7,20 +7,21 @@ menu "Display Engine Configuration"
 config DRM_AMD_DC
 	bool "AMD DC - Enable new display engine"
 	default y
-	depends on BROKEN || !CC_IS_CLANG || ARM64 || RISCV || SPARC64 || X86_64
+	depends on BROKEN || !CC_IS_CLANG || ARM64 || LOONGARCH || 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 && !(CC_IS_CLANG && (ARM64 || RISCV))
+	select DRM_AMD_DC_FP if ARCH_HAS_KERNEL_FPU_SUPPORT && !(CC_IS_CLANG && (ARM64 || LOONGARCH || RISCV))
 	help
 	  Choose this option if you want to use the new display engine
 	  support for AMDGPU. This adds required support for Vega and
 	  Raven ASICs.
 
-	  calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 || ARM64)
-	  architectures built with Clang (all released versions), whereby the stack
-	  frame gets blown up to well over 5k.  This would cause an immediate kernel
-	  panic on most architectures.  We'll revert this when the following bug report
-	  has been resolved: https://github.com/llvm/llvm-project/issues/41896.
+	  calculate_bandwidth() is presently broken on all !(X86_64 || SPARC64 ||
+	  ARM64 || LOONGARCH || RISCV) architectures built with Clang (all released
+	  versions), whereby the stack frame gets blown up to well over 5k.  This
+	  would cause an immediate kernel panic on most architectures.  We'll revert
+	  this when the following bug report has been resolved:
+	  https://github.com/llvm/llvm-project/issues/41896.
 
 config DRM_AMD_DC_FP
 	def_bool n