[PATCH v3 1/1] drm/amd/display: add DCN support for ARM64
Nathan Chancellor
nathan at kernel.org
Mon Oct 31 11:47:51 PDT 2022
Hi Rodrigo and Ao,
On Fri, Oct 28, 2022 at 08:48:26AM -0700, Nathan Chancellor wrote:
> On Fri, Oct 28, 2022 at 11:35:32AM -0400, Rodrigo Siqueira Jordao wrote:
> >
> >
> > On 2022-10-28 11:09, Nathan Chancellor wrote:
> > > Hi Ao,
> > >
> > > On Thu, Oct 27, 2022 at 09:52:29PM +0200, Ao Zhong wrote:
> > > > After moving all FPU code to the DML folder, we can enable DCN support
> > > > for the ARM64 platform. Remove the -mgeneral-regs-only CFLAG from the
> > > > code in the DML folder that needs to use hardware FPU, and add a control
> > > > mechanism for ARM Neon.
> > > >
> > > > Signed-off-by: Ao Zhong <hacc1225 at gmail.com>
> > > > ---
> > > > drivers/gpu/drm/amd/display/Kconfig | 2 +-
> > > > .../gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 6 ++++++
> > > > drivers/gpu/drm/amd/display/dc/dml/Makefile | 20 +++++++++++++++----
> > > > 3 files changed, 23 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
> > > > index 0142affcdaa3..a7f1c4e51719 100644
> > > > --- a/drivers/gpu/drm/amd/display/Kconfig
> > > > +++ b/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 || PPC64)
> > > > + select DRM_AMD_DC_DCN if (X86 || PPC64 || (ARM64 && KERNEL_MODE_NEON))
> > > > help
> > > > Choose this option if you want to use the new display engine
> > > > support for AMDGPU. This adds required support for Vega and
> > > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> > > > index ab0c6d191038..1743ca0a3641 100644
> > > > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> > > > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> > > > @@ -31,6 +31,8 @@
> > > > #elif defined(CONFIG_PPC64)
> > > > #include <asm/switch_to.h>
> > > > #include <asm/cputable.h>
> > > > +#elif defined(CONFIG_ARM64)
> > > > +#include <asm/neon.h>
> > > > #endif
> > > > /**
> > > > @@ -99,6 +101,8 @@ void dc_fpu_begin(const char *function_name, const int line)
> > > > preempt_disable();
> > > > enable_kernel_fp();
> > > > }
> > > > +#elif defined(CONFIG_ARM64)
> > > > + kernel_neon_begin();
> > > > #endif
> > > > }
> > > > @@ -136,6 +140,8 @@ void dc_fpu_end(const char *function_name, const int line)
> > > > disable_kernel_fp();
> > > > preempt_enable();
> > > > }
> > > > +#elif defined(CONFIG_ARM64)
> > > > + kernel_neon_end();
> > > > #endif
> > > > }
> > > > diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> > > > index d0c6cf61c676..d4e93bed1c8e 100644
> > > > --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
> > > > +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> > > > @@ -33,6 +33,10 @@ ifdef CONFIG_PPC64
> > > > dml_ccflags := -mhard-float -maltivec
> > > > endif
> > > > +ifdef CONFIG_ARM64
> > > > +dml_rcflags := -mgeneral-regs-only
> > > > +endif
> > > > +
> > > > ifdef CONFIG_CC_IS_GCC
> > > > ifeq ($(call cc-ifversion, -lt, 0701, y), y)
> > > > IS_OLD_GCC = 1
> > > > @@ -55,8 +59,6 @@ frame_warn_flag := -Wframe-larger-than=2048
> > > > endif
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/display_mode_lib.o := $(dml_ccflags)
> > > > -
> > > > -ifdef CONFIG_DRM_AMD_DC_DCN
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/display_mode_vba.o := $(dml_ccflags)
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/dcn10/dcn10_fpu.o := $(dml_ccflags)
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/dcn20/dcn20_fpu.o := $(dml_ccflags)
> > > > @@ -88,7 +90,6 @@ CFLAGS_$(AMDDALPATH)/dc/dml/calcs/dcn_calcs.o := $(dml_ccflags)
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/calcs/dcn_calc_auto.o := $(dml_ccflags)
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/calcs/dcn_calc_math.o := $(dml_ccflags) -Wno-tautological-compare
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/display_mode_vba.o := $(dml_rcflags)
> > > > -CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn2x/dcn2x.o := $(dml_rcflags)
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn20/display_mode_vba_20.o := $(dml_rcflags)
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn20/display_rq_dlg_calc_20.o := $(dml_rcflags)
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn20/display_mode_vba_20v2.o := $(dml_rcflags)
> > > > @@ -105,7 +106,18 @@ CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn32/display_mode_vba_util_32.o := $(dml_rcf
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn301/dcn301_fpu.o := $(dml_rcflags)
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/display_mode_lib.o := $(dml_rcflags)
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dsc/rc_calc_fpu.o := $(dml_rcflags)
> > > > -endif
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn10/dcn10_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn20/dcn20_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn314/display_mode_vba_314.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn314/display_rq_dlg_calc_314.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn314/dcn314_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn30/dcn30_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn32/dcn32_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn321/dcn321_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn31/dcn31_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn302/dcn302_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dcn303/dcn303_fpu.o := $(dml_rcflags)
> > > > +CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/calcs/dcn_calc_math.o := $(dml_rcflags)
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/dml1_display_rq_dlg_calc.o := $(dml_ccflags)
> > > > CFLAGS_$(AMDDALPATH)/dc/dml/display_rq_dlg_helpers.o := $(dml_ccflags)
> > > > CFLAGS_REMOVE_$(AMDDALPATH)/dc/dml/dml1_display_rq_dlg_calc.o := $(dml_rcflags)
> > > > --
> > > > 2.37.4
> > > >
> > >
> > > Enabling this code for arm64 reveals the following warnings when
> > > building allmodconfig with clang. A very recent change in LLVM added the
> > > variable and spill information so that will not be seen with older
> > > versions but I also saw the warnings with clang 15.0.0 from Fedora.
> > >
> > > drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn30/display_mode_vba_30.c:1852:13: error: stack frame size (2112) exceeds limit (2048) in 'DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerformanceCalculation' [-Werror,-Wframe-larger-than]
> > > static void DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerformanceCalculation(
> > > ^
> > > 1152/2112 (54.55%) spills, 960/2112 (45.45%) variables
> > >
> > > drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn30/display_mode_vba_30.c:3542:6: error: stack frame size (2240) exceeds limit (2048) in 'dml30_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
> > > void dml30_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
> > > ^
> > > 1451/2240 (64.78%) spills, 789/2240 (35.22%) variables
> > >
> > > drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn31/display_mode_vba_31.c:3791:6: error: stack frame size (2736) exceeds limit (2048) in 'dml31_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
> > > void dml31_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
> > > ^
> > > 1342/2736 (49.05%) spills, 1394/2736 (50.95%) variables
> > >
> > > drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn314/display_mode_vba_314.c:3890:6: error: stack frame size (2720) exceeds limit (2048) in 'dml314_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
> > > void dml314_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
> > > ^
> > > 1325/2720 (48.71%) spills, 1395/2720 (51.29%) variables
> > >
> > > drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:59:13: error: stack frame size (2208) exceeds limit (2048) in 'DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerformanceCalculation' [-Werror,-Wframe-larger-than]
> > > static void DISPCLKDPPCLKDCFCLKDeepSleepPrefetchParametersWatermarksAndPerformanceCalculation(
> > > ^
> > > 1397/2208 (63.27%) spills, 811/2208 (36.73%) variables
> > >
> > > drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn32/display_mode_vba_32.c:1681:6: error: stack frame size (2496) exceeds limit (2048) in 'dml32_ModeSupportAndSystemConfigurationFull' [-Werror,-Wframe-larger-than]
> > > void dml32_ModeSupportAndSystemConfigurationFull(struct display_mode_lib *mode_lib)
> > > ^
> > > 1504/2496 (60.26%) spills, 992/2496 (39.74%) variables
> > >
> > > I can try to take a look at these next week, as I have prior obligations
> > > today, unless others wanted to help me out ;)
> >
> > Hi Nathan,
> >
> > Thanks a lot for checking this.
> >
> > About those stack frame issues, I guess they are generic, right? I mean, I
> > don't see why we only see it if we enable arm64.
>
> I do not see these warnings on x86_64 as I had to tackle them for 6.0.
> powerpc allmodconfig is already broken with clang for other reasons so I
> am not sure if these warnings are there; I can try to test that. I am
> not sure why things are going sideways for arm64 with clang here but I
> would really like to keep allmodconfig building without any issues, as
> that is a good target for catching new warnings due to -Werror.
I was thinking about this over the weekend and I do not think it is fair
to hold up this change for these warnings, as I am not sure when I will
be able to investigate them fully. However, I still do not want to see
our builds broken over this. Would you consider adding the following
diff and sending a v4? This would allow others to look into and fix the
warnings if they have a vested interest in making this code compile with
clang on arm64, while not impacting people who use clang and do not care
about this code or people who just use GCC. Thoughts?
Cheers,
Nathan
diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
index a7f1c4e51719..843a55a6a3ac 100644
--- a/drivers/gpu/drm/amd/display/Kconfig
+++ b/drivers/gpu/drm/amd/display/Kconfig
@@ -6,7 +6,8 @@ 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 || PPC64 || (ARM64 && KERNEL_MODE_NEON))
+ # !CC_IS_CLANG: https://github.com/ClangBuiltLinux/linux/issues/1752
+ select DRM_AMD_DC_DCN if (X86 || PPC64 || (ARM64 && KERNEL_MODE_NEON && !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
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