RDY bit clarification

[Keith Busch]

On Sun, Jan 14, 2018 at 09:26:23AM +0530, muthu crazy wrote:
> Why does linux nvme target code is checking for NVME_CSTS_RDY == 1
> before submitting any IO commands to device. Is there any chance RDY
> can go down after the controller initialization. It make sense if we
> check for CFS instead of RDY.
> 
> Isn't causing performance drop?

I don't think it's for situations where RDY goest down on it's own, but
for checking if a badly behaving host sends a command before respecting
the proper state transitions.