Clarification on moving to drm-stable-kmod on 11.2

[Kevin Oberman]

On Sat, Aug 11, 2018 at 3:54 PM Greg V <greg at unrelenting.technology> wrote:

>
>
> On Sun, Aug 12, 2018 at 1:12 AM, Pete Wright <pete at nomadlogic.org>
> wrote:
> >
> >
> > On Aug 11, 2018 1:44 PM, Greg V <greg at unrelenting.technology> wrote:
> >> On Sat, Aug 11, 2018 at 9:58 PM, Kevin Oberman <rkoberman at gmail.com>
> >> wrote:
> >> > A while ago I moved to running drm-stable-kmod on my 11.2 system
> >> and
> >> > have
> >> > not had any issues, but I am unclear on what, if ny changes are
> >> > appropriate
> >> > in my loader.conf. I just noticed that the "old" kernel module is
> >> > atill
> >> > being loaded and I think that is wrong.
> >> >
> >> > My loader.conf contains:
> >> > drm.i915.enable_rc6=7
> >> > # Enable semaphores
> >> > drm.i915.semaphores=1
> >> > Are these appropriate to drm-stable-kmod? If so, is loader.conf the
> >> > proper
> >> > place for them?
> >>
> >> Hi,
> >>
> >> These don't work with drm-*-kmod, the new names are:
> >> compat.linuxkpi.enable_rc6, compat.linuxkpi.semaphores, etc.
> >>
> >> And yeah, loader.conf is of course the right place.
> >>
> >> You can run 'sysctl -a | grep enable_rc6' — if you see drm.i915,
> >> you're on the old module, if you see compat.linuxkpi, you're on the
> >> new
> >> one.
> >>
> >
> >
> > Out of curiosity, what do these knobs do?  Or for the semaphor knob,
> > when would you use this?
>
> rc6 is a lower power state. I think it should be enabled by default
> anyway.
>
> semaphores enables, well, semaphores, for some synchronization in the
> driver somewhere… idk really :) also should probably be default=1
>

Thanks! For the record, I see that  compat.linuxkpi.enable_rc6 is set to 1
by default, but it's not clear which of the rc6 bits are set. If it is just
1, not all power savings are enabled, but it might now be a boolean and
setting it sets all three rc6 bits. I know that I needed to enable the
semaphores for some port, but I don't recall what it was. It now defaults
to 1, as well.

Thanks for the responses.
--
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: rkoberman at gmail.com
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683