Am 06.11.19 um 18:26 schrieb Zeng, Oak:
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.
Change-Id: I02c2a27cd0dbc205498eb86aafa722f2e0c25fe6
Signed-off-by: Oak Zeng <oak.z...@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
index 555d8e5..1356ff9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
@@ -127,18 +127,44 @@ struct amdgpu_xgmi {
};
struct amdgpu_gmc {
+ /* FB's physical address in MMIO space (for CPU to
+ * map FB). This is different compared to the apg/
+ * 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;
+ /* APG 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 is used to simulate FB in ZFB case
+ */
Really nice improvement. Alex noted as well please mention the page
table use case here as well.
Additional to that we also have a use case for display scanout, but that
one is currently not implemented yet. Might be a good idea to mention
that as well.
With that fixed the patch is Reviewed-by: Christian König
<christian.koe...@amd.com>.
Regards,
Christian.
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
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