Merge tag 'powerpc-5.19-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc fixes from Michael Ellerman:

 - Re-enable the new amdgpu display engine for powerpc, as long as the
   compiler is correctly configured.

 - Disable stack variable initialisation in prom_init to fix GCC 12
   allmodconfig.

Thanks to Dan Horák and Sudip Mukherjee.

* tag 'powerpc-5.19-6' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  drm/amdgpu: Re-enable DCN for 64-bit powerpc
  powerpc/64s: Disable stack variable initialisation for prom_init

arch/powerpc/Kconfig

@@ -282,6 +282,10 @@ config PPC
 	# Please keep this list sorted alphabetically.
 	#
 
+config PPC_LONG_DOUBLE_128
+	depends on PPC64
+	def_bool $(success,test "$(shell,echo __LONG_DOUBLE_128__ | $(CC) -E -P -)" = 1)
+
 config PPC_BARRIER_NOSPEC
 	bool
 	default y

arch/powerpc/kernel/Makefile

@@ -20,6 +20,7 @@ CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
 CFLAGS_prom_init.o += -fno-stack-protector
 CFLAGS_prom_init.o += -DDISABLE_BRANCH_PROFILING
 CFLAGS_prom_init.o += -ffreestanding
+CFLAGS_prom_init.o += $(call cc-option, -ftrivial-auto-var-init=uninitialized)
 
 ifdef CONFIG_FUNCTION_TRACER
 # Do not trace early boot code

drivers/gpu/drm/amd/display/Kconfig

@@ -6,7 +6,7 @@ config DRM_AMD_DC
 	bool "AMD DC - Enable new display engine"
 	default y
 	select SND_HDA_COMPONENT if SND_HDA_CORE
-	select DRM_AMD_DC_DCN if X86 && !(KCOV_INSTRUMENT_ALL && KCOV_ENABLE_COMPARISONS)
+	select DRM_AMD_DC_DCN if (X86 || PPC_LONG_DOUBLE_128) && !(KCOV_INSTRUMENT_ALL && KCOV_ENABLE_COMPARISONS)
 	help
 	  Choose this option if you want to use the new display engine
 	  support for AMDGPU. This adds required support for Vega and