Re: [PATCH v2 4/4] PCI: Add runtime PM support for PCIe ports

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Friday, April 22, 2016 12:10:26 PM Mika Westerberg wrote:
> On Fri, Apr 22, 2016 at 02:26:22AM +0200, Rafael J. Wysocki wrote:
> > On Fri, Apr 22, 2016 at 1:25 AM, Andreas Noever
> > <andreas.noever@gmail.com> wrote:
> > > On Thu, Apr 21, 2016 at 9:19 PM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > >> On Thursday, April 21, 2016 04:12:24 PM Mika Westerberg wrote:
> > >>> On Wed, Apr 20, 2016 at 10:23:33PM +0200, Rafael J. Wysocki wrote:
> > >>> > Breaking any systems that work today is not an option.  if that
> > >>> > happens, the commit that has done that is a clear candidate for
> > >>> > reverting.
> > >>>
> > >>> Understood, thanks.
> > >>>
> > >>> BTW, do you have any preference regarding the cut-off date?
> > >>
> > >> Some time around when machines with Windows 10 started to ship should be
> > >> relatively safe.
> > >>
> > >> I guess we can just pick a reasonable date in the initial patch and then
> > >> try to move it back to the past subsequently and see if that breaks things
> > >> for anyone.
> > >
> > > Maybe add a boot option to overwrite the heuristic (in both
> > > directions) to allow people to test this on older machines and
> > > pinpoint breakage on newer machines?
> > 
> > Yes, a kernel command line override would be fine by me.
> 
> OK, so to summarize:
> 
>  - Use cut-off date 2015 which is the year Windows 10 was released
> 
>  - Add command line parameter that allows this to be overridden.
>    Something like:
> 
> 	pcie_port_pm=   [PCIE] PCIe port power management handling:
> 		off     Disable power management off all PCIe ports
> 		force   Forcibly enable power management of all PCIe ports

Correct, unless Bjorn has a differing opinion.

Bjorn?