drm/amdgpu: assign fb_start/end in mmhub v9.4 interface

Align with mmhub v1.0.
Signed-off-by: NLe Ma <le.ma@amd.com>
Reviewed-by: NFeifei Xu <Feifei.Xu@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/mmhub_v9_4.c

@@ -39,10 +39,17 @@ u64 mmhub_v9_4_get_fb_location(struct amdgpu_device *adev)
 {
 	/* The base should be same b/t 2 mmhubs on Acrturus. Read one here. */
 	u64 base = RREG32_SOC15(MMHUB, 0, mmVMSHAREDVC0_MC_VM_FB_LOCATION_BASE);
+	u64 top = RREG32_SOC15(MMHUB, 0, mmVMSHAREDVC0_MC_VM_FB_LOCATION_TOP);
 
 	base &= VMSHAREDVC0_MC_VM_FB_LOCATION_BASE__FB_BASE_MASK;
 	base <<= 24;
 
+	top &= VMSHAREDVC0_MC_VM_FB_LOCATION_TOP__FB_TOP_MASK;
+	top <<= 24;
+
+	adev->gmc.fb_start = base;
+	adev->gmc.fb_end = top;
+
 	return base;
 }