In following topic, it seems that current Xavier cannot support 2.5Gsps officially.
(https://devtalk.nvidia.com/default/topic/1063856/jetson-agx-xavier/c-phy-interfacing-in-agx-xavier/post/5393248/#reply)
Is there any procedure, tweak, or hints to operate up to 2.5Gsps even for a single trio ?