linux-kernel - Re: [PATCH] drm/amd/display: Add missing hard-float compile flags for PPC64 builds

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Date:   Mon, 20 Jun 2022 17:51:04 -0400
From:   Alex Deucher <alexdeucher@...il.com>
To:     Guenter Roeck <linux@...ck-us.net>, Melissa Wen <mwen@...lia.com>,
        "Siqueira, Rodrigo" <Rodrigo.Siqueira@....com>,
        "Dhillon, Jasdeep" <Jasdeep.Dhillon@....com>
Cc:     Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        LKML <linux-kernel@...r.kernel.org>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        David Airlie <airlied@...ux.ie>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        Daniel Axtens <dja@...ens.net>
Subject: Re: [PATCH] drm/amd/display: Add missing hard-float compile flags for
 PPC64 builds

On Sat, Jun 18, 2022 at 7:27 PM Guenter Roeck <linux@...ck-us.net> wrote:
>
> ppc:allmodconfig builds fail with the following error.
>
> powerpc64-linux-ld:
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dml/display_mode_lib.o
>                 uses hard float,
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dcn31/dcn31_resource.o
>                 uses soft float
> powerpc64-linux-ld:
>         failed to merge target specific data of file
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dcn31/dcn31_resource.o
> powerpc64-linux-ld:
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dml/display_mode_lib.o
>                 uses hard float,
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dcn315/dcn315_resource.o
>                 uses soft float
> powerpc64-linux-ld:
>         failed to merge target specific data of
>         file drivers/gpu/drm/amd/amdgpu/../display/dc/dcn315/dcn315_resource.o
> powerpc64-linux-ld:
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dml/display_mode_lib.o
>                 uses hard float,
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dcn316/dcn316_resource.o
>                 uses soft float
> powerpc64-linux-ld:
>         failed to merge target specific data of file
>         drivers/gpu/drm/amd/amdgpu/../display/dc/dcn316/dcn316_resource.o
>
> The problem was introduced with commit 41b7a347bf14 ("powerpc: Book3S
> 64-bit outline-only KASAN support") which adds support for KASAN. This
> commit in turn enables DRM_AMD_DC_DCN because KCOV_INSTRUMENT_ALL and
> KCOV_ENABLE_COMPARISONS are no longer enabled. As result, new files are
> compiled which lack the selection of hard-float.
>
> Fixes: 41b7a347bf14 ("powerpc: Book3S 64-bit outline-only KASAN support")
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Daniel Axtens <dja@...ens.net>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
>  drivers/gpu/drm/amd/display/dc/dcn31/Makefile  | 4 ++++
>  drivers/gpu/drm/amd/display/dc/dcn315/Makefile | 4 ++++
>  drivers/gpu/drm/amd/display/dc/dcn316/Makefile | 4 ++++
>  3 files changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn31/Makefile b/drivers/gpu/drm/amd/display/dc/dcn31/Makefile
> index ec041e3cda30..74be02114ae4 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn31/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dcn31/Makefile
> @@ -15,6 +15,10 @@ DCN31 = dcn31_resource.o dcn31_hubbub.o dcn31_hwseq.o dcn31_init.o dcn31_hubp.o
>         dcn31_apg.o dcn31_hpo_dp_stream_encoder.o dcn31_hpo_dp_link_encoder.o \
>         dcn31_afmt.o dcn31_vpg.o
>
> +ifdef CONFIG_PPC64
> +CFLAGS_$(AMDDALPATH)/dc/dcn31/dcn31_resource.o := -mhard-float -maltivec
> +endif

This stuff was all moved as part of the FP rework in:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=26f4712aedbdf4b9f5e3888a50a2a4b130ee4a9b
@Siqueira, Rodrigo
, @Melissa Wen, @Dhillon, Jasdeep  can you take a look to understand
why this is necessary?  If we add back the PPC flags, I think we need
to add back the x86 ones as well.

Alex

> +
>  AMD_DAL_DCN31 = $(addprefix $(AMDDALPATH)/dc/dcn31/,$(DCN31))
>
>  AMD_DISPLAY_FILES += $(AMD_DAL_DCN31)
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn315/Makefile b/drivers/gpu/drm/amd/display/dc/dcn315/Makefile
> index 59381d24800b..1395c1ced8c5 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn315/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dcn315/Makefile
> @@ -25,6 +25,10 @@
>
>  DCN315 = dcn315_resource.o
>
> +ifdef CONFIG_PPC64
> +CFLAGS_$(AMDDALPATH)/dc/dcn315/dcn315_resource.o := -mhard-float -maltivec
> +endif
> +
>  AMD_DAL_DCN315 = $(addprefix $(AMDDALPATH)/dc/dcn315/,$(DCN315))
>
>  AMD_DISPLAY_FILES += $(AMD_DAL_DCN315)
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn316/Makefile b/drivers/gpu/drm/amd/display/dc/dcn316/Makefile
> index 819d44a9439b..c3d2dd78f1e2 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn316/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dcn316/Makefile
> @@ -25,6 +25,10 @@
>
>  DCN316 = dcn316_resource.o
>
> +ifdef CONFIG_PPC64
> +CFLAGS_$(AMDDALPATH)/dc/dcn316/dcn316_resource.o := -mhard-float -maltivec
> +endif
> +
>  AMD_DAL_DCN316 = $(addprefix $(AMDDALPATH)/dc/dcn316/,$(DCN316))
>
>  AMD_DISPLAY_FILES += $(AMD_DAL_DCN316)
> --
> 2.35.1
>