drm/amdgpu: Add documentation for memory info

Add the amdgpu.rst tie-ins for the mem_info documentation
Signed-off-by: NKent Russell <kent.russell@amd.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

Documentation/gpu/amdgpu.rst

@@ -226,3 +226,44 @@ serial_number
 
 .. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
    :doc: serial_number
+
+GPU Memory Usage Information
+============================
+
+Various memory accounting can be accessed via sysfs
+
+mem_info_vram_total
+-------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vram_total
+
+mem_info_vram_used
+------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vram_used
+
+mem_info_vis_vram_total
+-----------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vis_vram_total
+
+mem_info_vis_vram_used
+----------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+   :doc: mem_info_vis_vram_used
+
+mem_info_gtt_total
+-----------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+   :doc: mem_info_gtt_total
+
+mem_info_gtt_used
+------------------
+
+.. kernel-doc:: drivers/gpu/drm/amd/amdgpu/amdgpu_gtt_mgr.c
+   :doc: mem_info_gtt_used