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Subject[PATCH 5.2 10/45] drm/amd/display: readd -msse2 to prevent Clang from emitting libcalls to undefined SW FP routines
From: Nick Desaulniers <>

[ Upstream commit 0f0727d971f6fdf8f1077180d495ddb9928f0c8b ]

arch/x86/Makefile disables SSE and SSE2 for the whole kernel. The
AMDGPU drivers modified in this patch re-enable SSE but not SSE2. Turn
on SSE2 to support emitting double precision floating point instructions
rather than calls to non-existent (usually available from gcc_s or
compiler_rt) floating point helper routines for Clang.

This was originally landed in:
commit 10117450735c ("drm/amd/display: add -msse2 to prevent Clang from emitting libcalls to undefined SW FP routines")
but reverted in:
commit 193392ed9f69 ("Revert "drm/amd/display: add -msse2 to prevent Clang from emitting libcalls to undefined SW FP routines"")
due to bugreports from GCC builds. Add guards to only do so for Clang.


Suggested-by: Sedat Dilek <>
Suggested-by: Sami Tolvanen <>
Signed-off-by: Nick Desaulniers <>
Signed-off-by: Alex Deucher <>
Signed-off-by: Sasha Levin <>
drivers/gpu/drm/amd/display/dc/calcs/Makefile | 4 ++++
drivers/gpu/drm/amd/display/dc/dml/Makefile | 4 ++++
2 files changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/calcs/Makefile b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
index 95f332ee3e7e6..16614d73a5fcf 100644
--- a/drivers/gpu/drm/amd/display/dc/calcs/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/calcs/Makefile
@@ -32,6 +32,10 @@ endif

calcs_ccflags := -mhard-float -msse $(cc_stack_align)

+calcs_ccflags += -msse2
CFLAGS_dcn_calcs.o := $(calcs_ccflags)
CFLAGS_dcn_calc_auto.o := $(calcs_ccflags)
CFLAGS_dcn_calc_math.o := $(calcs_ccflags) -Wno-tautological-compare
diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
index d97ca6528f9d9..934ffe1b4b00e 100644
--- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
+++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
@@ -32,6 +32,10 @@ endif

dml_ccflags := -mhard-float -msse $(cc_stack_align)

+dml_ccflags += -msse2
CFLAGS_display_mode_lib.o := $(dml_ccflags)
CFLAGS_display_pipe_clocks.o := $(dml_ccflags)
CFLAGS_dml1_display_rq_dlg_calc.o := $(dml_ccflags)

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