On Mon, May 13, 2019 at 02:43:43PM +0000, mario.limoncie...@dell.com wrote: > > Well, it sounds like your partners device does not work properly in this > > case. There is nothing in the NVMe spec that says queues should be > > torn down for deep power states, and that whole idea seems rather > > counter productive to low-latency suspend/resume cycles. > > Well I've got a thought, quoting the NVME spec: > "After a successful completion of a Set Features command for this feature, > the controller shall be in the > Power State specified. If enabled, autonomous power state transitions > continue to occur from the new state." > > If APST is enabled on this disk, what is to stop an autonomous reverse > transition from queue activity on the way down?
Regardless of whether APST is enabled or not, the controller may autonomously transition out of a host requested low power state in response to host activity. Exiting a low power state should mean some other task is actively using the device, and if that's the case, why are you trying to enter a low power state in the first place? Alternatively, if host activity really is idle, then why is the device autonomously leaving the requested state?
