From f6baa07497fbebcc05096097dfd9f32b8caa50b1 Mon Sep 17 00:00:00 2001 From: Oak Zeng Date: Wed, 6 Nov 2019 11:18:54 -0600 Subject: [PATCH] drm/amdgpu: Add comments to gmc structure MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Explain fields like aper_base, agp_start etc. The definition of those fields are confusing as they are from different view (CPU or GPU). Add comments for easier understand. Signed-off-by: Oak Zeng Reviewed-by: Alex Deucher Reviewed-by: Christian König Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h | 30 +++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h index 555d8e57fae9..406736a1bd3d 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h @@ -127,18 +127,48 @@ struct amdgpu_xgmi { }; struct amdgpu_gmc { + /* FB's physical address in MMIO space (for CPU to + * map FB). This is different compared to the agp/ + * gart/vram_start/end field as the later is from + * GPU's view and aper_base is from CPU's view. + */ resource_size_t aper_size; resource_size_t aper_base; /* for some chips with <= 32MB we need to lie * about vram size near mc fb location */ u64 mc_vram_size; u64 visible_vram_size; + /* AGP aperture start and end in MC address space + * Driver find a hole in the MC address space + * to place AGP by setting MC_VM_AGP_BOT/TOP registers + * Under VMID0, logical address == MC address. AGP + * aperture maps to physical bus or IOVA addressed. + * AGP aperture is used to simulate FB in ZFB case. + * AGP aperture is also used for page table in system + * memory (mainly for APU). + * + */ u64 agp_size; u64 agp_start; u64 agp_end; + /* GART aperture start and end in MC address space + * Driver find a hole in the MC address space + * to place GART by setting VM_CONTEXT0_PAGE_TABLE_START/END_ADDR + * registers + * Under VMID0, logical address inside GART aperture will + * be translated through gpuvm gart page table to access + * paged system memory + */ u64 gart_size; u64 gart_start; u64 gart_end; + /* Frame buffer aperture of this GPU device. Different from + * fb_start (see below), this only covers the local GPU device. + * Driver get fb_start from MC_VM_FB_LOCATION_BASE (set by vbios) + * and calculate vram_start of this local device by adding an + * offset inside the XGMI hive. + * Under VMID0, logical address == MC address + */ u64 vram_start; u64 vram_end; /* FB region , it's same as local vram region in single GPU, in XGMI -- 2.20.1