drm/amdgpu/gfx8: reserve kiq eop object before unmapping it

It's required.
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v8_0.c

@@ -1488,7 +1488,11 @@ static int gfx_v8_0_kiq_init(struct amdgpu_device *adev)
 
 	memset(hpd, 0, MEC_HPD_SIZE);
 
+	r = amdgpu_bo_reserve(kiq->eop_obj, false);
+	if (unlikely(r != 0))
+		dev_warn(adev->dev, "(%d) reserve kiq eop bo failed\n", r);
 	amdgpu_bo_kunmap(kiq->eop_obj);
+	amdgpu_bo_unreserve(kiq->eop_obj);
 
 	return 0;
 }