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

[WANG Xuerui]

On 2023/5/5 19:32, 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.

Some grammatical fixes and paraphrasing:

"LoongArch now provides kernel_fpu_{begin,end} that are used like the 
x86 counterparts in commit 2b3bd32ea3a22ea2d ("LoongArch: Provide kernel 
fpu functions"), so we can now implement DRM_AMD_DC_FP on LoongArch for 
supporting more DCN devices."

> 
> Signed-off-by: WANG Xuerui <kernel at xen0n.name>
> Signed-off-by: Huacai Chen <chenhuacai at loongson.cn>

I just finished my tests according to the link above and all seems fine.

* Board: A2101 (Loongson 3A5000 with LS7A1000 bridge)
   - with the firmware provided at [1]
* GPU: RX 6400 (PowerColor ITX RX6400 4GB GDDR6)
* Display: Dell P2317H (connected via DisplayPort)
* Kernel: next-20230505 with this patch (with the conflict resolved)
* Sysroot: up-to-date Gentoo/LoongArch

I've tested:

* Desktop sessions: Xfce4, Plasma Wayland
* Hot-plugging
   - at tty, at sddm, inside Plasma Wayland session, multiple times each
* Changing resolutions
* kms_flip tests: every non-skipped case passed (I can't test 
dual-monitor right now)

[1]: https://github.com/loongson/Firmware/tree/main/5000Series/PC/A2101

Hence it's:

Tested-by: WANG Xuerui <kernel at xen0n.name>

> ---
> 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();

And with the conflict here with linux-next resolved then we may be good 
to go.

>   #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

-- 
WANG "xen0n" Xuerui

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