[PATCH] nvme/pci: default to simple suspend

[Christoph Hellwig]

On Wed, Feb 02, 2022 at 08:03:34AM -0800, Keith Busch wrote:
> On Wed, Feb 02, 2022 at 08:55:02AM +0100, Christoph Hellwig wrote:
> > On Tue, Feb 01, 2022 at 08:50:06AM -0800, Keith Busch wrote:
> > > There is no complete set of attributes a driver can check to know if
> > > nvme power management is the correct thing to do in a runtime suspend
> > > situation. Every attempt so far to optimize idle power consumption and
> > > resume latency for a particular platform just leads to regressions
> > > elsewhere.
> > > 
> > > Default to the simple shutdown since it is the historically safest
> > > option, and provide a user parameter to override it if the user knows
> > > it's safe to use for their platform.
> > 
> > Sigh.  The platforms really should be asking for a explicit D3cold if
> > they need one..
> 
> It's too late now, but perhaps the new property should have been
> inverted since preparing for D3 was the previous default behavior;
> platforms could have instead explicitly asked for "no-D3" if they wanted
> it. That would have been easier for backward compatibility.

I'd really prefer to sort this out at the platform level.  We can't work
around broken platforms in nvme forever.