Microsoft uses FPGAs for Deep Learning. Source:

https://techcrunch.com/2017/08/22/microsoft-brainwave-aims-t...

... for inference. I don't know of anyone who takes training on FPGAs seriously. They tend to get crushed by GPU/TPU/other ASIC in throughput, perf/watt, and perf/$.

Training on FPGAs starts to make a lot of sense when you consider low bit precision computation (e.g. DoReFa-Net).