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

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Hi,

On 5/5/23 21:39, Hamza Mahfooz wrote:

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@xxxxxxx/

Thanks for the helpful link!

I did test an earlier version of this patch along with the arch/loongarch kernel FPU bits before that patch got upstreamed, with a RX 6400 (BEIGE_GOBY) on a Loongson 3A5000 + LS7A1000 system (by far the most popular combination for LoongArch desktops). Things like Plasma Wayland session or glmark2 work just fine, although I didn't go for the more complete testing as detailed in the mail you linked to. I'll try going through that procedure in the next 1~2 days when I have time & get physical access to that box.

On a side note, I had to modprobe amdgpu with runpm=0, otherwise my dmesg gets flooded with PSP getting resumed every 8~10 seconds or so. I currently have none of the connectors plugged in. I didn't notice any similar reports on the Internet so I don't know if it's due to platform quirks or not.


Signed-off-by: WANG Xuerui <kernel@xxxxxxxxxx>
Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
---
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();
This is going to conflict with commit b1bcdd409d2d ("drm/amd/display: Disable migration to ensure consistency of per-CPU variable"), which is present in next-20230505. Resolution is trivial though.
  #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

Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/




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