linux-kernel - Re: [PATCH v4 12/15] drm/amd/display: Only use hard-float, not altivec on powerpc

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Date: Tue, 30 Apr 2024 13:28:37 -0400
From: Harry Wentland <harry.wentland@....com>
To: Samuel Holland <samuel.holland@...ive.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 linux-arm-kernel@...ts.infradead.org, x86@...nel.org
Cc: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
 linuxppc-dev@...ts.ozlabs.org, linux-riscv@...ts.infradead.org,
 Christoph Hellwig <hch@....de>, loongarch@...ts.linux.dev,
 amd-gfx@...ts.freedesktop.org, Michael Ellerman <mpe@...erman.id.au>,
 Alex Deucher <alexander.deucher@....com>
Subject: Re: [PATCH v4 12/15] drm/amd/display: Only use hard-float, not
 altivec on powerpc

On 2024-03-29 03:18, Samuel Holland wrote:
> From: Michael Ellerman <mpe@...erman.id.au>
> 
> The compiler flags enable altivec, but that is not required; hard-float
> is sufficient for the code to build and function.
> 
> Drop altivec from the compiler flags and adjust the enable/disable code
> to only enable FPU use.
> 
> Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> Acked-by: Alex Deucher <alexander.deucher@....com>
> Signed-off-by: Samuel Holland <samuel.holland@...ive.com>

Acked-by: Harry Wentland <harry.wentland@....com>

Harry

> ---
> 
> (no changes since v2)
> 
> Changes in v2:
>  - New patch for v2
> 
>  drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 12 ++----------
>  drivers/gpu/drm/amd/display/dc/dml/Makefile    |  2 +-
>  drivers/gpu/drm/amd/display/dc/dml2/Makefile   |  2 +-
>  3 files changed, 4 insertions(+), 12 deletions(-)
> 
> 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 4ae4720535a5..0de16796466b 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> @@ -92,11 +92,7 @@ void dc_fpu_begin(const char *function_name, const int line)
>  #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
>  		kernel_fpu_begin();
>  #elif defined(CONFIG_PPC64)
> -		if (cpu_has_feature(CPU_FTR_VSX_COMP))
> -			enable_kernel_vsx();
> -		else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP))
> -			enable_kernel_altivec();
> -		else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE))
> +		if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE))
>  			enable_kernel_fp();
>  #elif defined(CONFIG_ARM64)
>  		kernel_neon_begin();
> @@ -125,11 +121,7 @@ void dc_fpu_end(const char *function_name, const int line)
>  #if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
>  		kernel_fpu_end();
>  #elif defined(CONFIG_PPC64)
> -		if (cpu_has_feature(CPU_FTR_VSX_COMP))
> -			disable_kernel_vsx();
> -		else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP))
> -			disable_kernel_altivec();
> -		else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE))
> +		if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE))
>  			disable_kernel_fp();
>  #elif defined(CONFIG_ARM64)
>  		kernel_neon_end();
> diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> index c4a5efd2dda5..59d3972341d2 100644
> --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> @@ -31,7 +31,7 @@ dml_ccflags := $(dml_ccflags-y) -msse
>  endif
>  
>  ifdef CONFIG_PPC64
> -dml_ccflags := -mhard-float -maltivec
> +dml_ccflags := -mhard-float
>  endif
>  
>  ifdef CONFIG_ARM64
> diff --git a/drivers/gpu/drm/amd/display/dc/dml2/Makefile b/drivers/gpu/drm/amd/display/dc/dml2/Makefile
> index acff3449b8d7..7b51364084b5 100644
> --- a/drivers/gpu/drm/amd/display/dc/dml2/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dml2/Makefile
> @@ -30,7 +30,7 @@ dml2_ccflags := $(dml2_ccflags-y) -msse
>  endif
>  
>  ifdef CONFIG_PPC64
> -dml2_ccflags := -mhard-float -maltivec
> +dml2_ccflags := -mhard-float
>  endif
>  
>  ifdef CONFIG_ARM64