[PATCH V2] drm/amdgpu/display: Enable DC_FP for LoongArch

[Hamza Mahfooz]

Hey Huacai,

On 5/5/23 07:32, Huacai Chen wrote:
> Now LoongArch provides kernel_fpu_begin() and kernel_fpu_end() in commit
> 2b3bd32ea3a22ea2d ("LoongArch: Provide kernel fpu functions"), so we can
> enable DC_FP for DCN devices.

Have you had the chance to test how well this is working on actual
hardware, or was it only compile tested? If it was only compile tested,
it would be great if you could run some tests. Please see the following
for more details:
https://lore.kernel.org/amd-gfx/8eb69dfb-ae35-dbf2-3f82-e8cc00e5389a@amd.com/

> 
> Signed-off-by: WANG Xuerui <kernel at xen0n.name>
> Signed-off-by: Huacai Chen <chenhuacai at loongson.cn>
> ---
> V2: Update commit message to add the commit which provides kernel fpu
>      functions.
> 
>   drivers/gpu/drm/amd/display/Kconfig            | 2 +-
>   drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 6 ++++--
>   drivers/gpu/drm/amd/display/dc/dml/Makefile    | 5 +++++
>   3 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/Kconfig b/drivers/gpu/drm/amd/display/Kconfig
> index 2d8e55e29637..49df073962d5 100644
> --- a/drivers/gpu/drm/amd/display/Kconfig
> +++ b/drivers/gpu/drm/amd/display/Kconfig
> @@ -8,7 +8,7 @@ config DRM_AMD_DC
>   	depends on BROKEN || !CC_IS_CLANG || X86_64 || SPARC64 || ARM64
>   	select SND_HDA_COMPONENT if SND_HDA_CORE
>   	# !CC_IS_CLANG: https://github.com/ClangBuiltLinux/linux/issues/1752
> -	select DRM_AMD_DC_FP if (X86 || (PPC64 && ALTIVEC) || (ARM64 && KERNEL_MODE_NEON && !CC_IS_CLANG))
> +	select DRM_AMD_DC_FP if (X86 || LOONGARCH || (PPC64 && ALTIVEC) || (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
> 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 1743ca0a3641..86f4c0e04654 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
> @@ -33,6 +33,8 @@
>   #include <asm/cputable.h>
>   #elif defined(CONFIG_ARM64)
>   #include <asm/neon.h>
> +#elif defined(CONFIG_LOONGARCH)
> +#include <asm/fpu.h>
>   #endif
>   
>   /**
> @@ -88,7 +90,7 @@ void dc_fpu_begin(const char *function_name, const int line)
>   	*pcpu += 1;
>   
>   	if (*pcpu == 1) {
> -#if defined(CONFIG_X86)
> +#if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
>   		kernel_fpu_begin();
>   #elif defined(CONFIG_PPC64)
>   		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
> @@ -127,7 +129,7 @@ void dc_fpu_end(const char *function_name, const int line)
>   	pcpu = get_cpu_ptr(&fpu_recursion_depth);
>   	*pcpu -= 1;
>   	if (*pcpu <= 0) {
> -#if defined(CONFIG_X86)
> +#if defined(CONFIG_X86) || defined(CONFIG_LOONGARCH)
>   		kernel_fpu_end();
>   #elif defined(CONFIG_PPC64)
>   		if (cpu_has_feature(CPU_FTR_VSX_COMP)) {
> diff --git a/drivers/gpu/drm/amd/display/dc/dml/Makefile b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> index 01db035589c5..542962a93e8f 100644
> --- a/drivers/gpu/drm/amd/display/dc/dml/Makefile
> +++ b/drivers/gpu/drm/amd/display/dc/dml/Makefile
> @@ -38,6 +38,11 @@ ifdef CONFIG_ARM64
>   dml_rcflags := -mgeneral-regs-only
>   endif
>   
> +ifdef CONFIG_LOONGARCH
> +dml_ccflags := -mfpu=64
> +dml_rcflags := -msoft-float
> +endif
> +
>   ifdef CONFIG_CC_IS_GCC
>   ifneq ($(call gcc-min-version, 70100),y)
>   IS_OLD_GCC = 1
-- 
Hamza