Re: [Ksummit-discuss] [TECH TOPIC] System-wide interface to specify the level of PM tuning

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

On Friday, July 17, 2015 01:41:56 PM Daniel Vetter wrote:
> On Thu, Jul 16, 2015 at 5:58 PM, Greg KH <greg@kroah.com> wrote:
> > On Thu, Jul 16, 2015 at 08:53:02AM -0700, Josh Triplett wrote:
> >> But the kernel already has quirk tables for various hardware, and that
> >> seems appropriate to continue putting in the kernel.
> >
> > For some types of devices, sure.  For others, like broken USB keyboards
> > that can't handle autosuspend, no.  For those we need a userspace
> > _whitelist_ that udev can use.  So there's no one answer that works for
> > all types of quirks.
> 
> Whether white or blacklist or some other mixed thing doesn't really
> matter. Imo the important part is that driver maintainers are in the
> best position to maintain that, and pushing it out to anyone else is
> just really not doing our jobs. And I think for most of these quirk
> lists the kernel does seem like the most appropriate place. If the
> list becomes giantic then we can move it to userspace (if that's
> really a problem, afaik no one proposed yet to move device match
> tables into userspace either and that's kinda the same thing really).
> But as long as there's no white/black/whatever list yet starting in
> the kernel is imo the right place.

Well, I'm wondering, then, why i915.enable_psr is not enabled by default,
for one example?

Failing to enable it prevents some SoCs from using the deepest available
C-states which in turn hurts battery life of the systems containing them
quite a bit, so there surely is a reason to have it enabled.

Thanks,
Rafael