[Intel-gfx] drm/i915: don't change DRM configuration when releasing load detect pipe

[Jesse Barnes]

On Fri, 9 Jul 2010 08:30:11 -0700
Jesse Barnes <jbarnes at virtuousgeek.org> wrote:

> On Mon, 08 Mar 2010 21:59:29 +0100
> Brice Goglin <Brice.Goglin at gmail.com> wrote:
> 
> > Eric Anholt wrote:
> > > On Thu, 18 Feb 2010 14:51:54 -0800, Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> > >   
> > >> When we get a CRTC to use for load detection, we restore its DPMS state
> > >> if needed.  We shouldn't, however, change the DRM configuration by
> > >> calling drm_helper_disable_unused_functions when we release the CRTC.
> > >> Doing so can cause problems with resume, since at suspend or lid close
> > >> time, X may choose to probe outputs.  If it doesn't re-probe them at
> > >> open or resume time, LVDS won't be restored, since
> > >> drm_helper_disable_unused_functions will have turned it off, preventing
> > >> the mode set at lid open from restoring it.
> > >>     
> > >
> > > It seems to me like the bug is that drm_helper_disable_unused_functions
> > > whacks the configuration.  Why should it do that?
> > >
> > > 		if (connector->status == connector_status_disconnected)
> > > 			connector->encoder = NULL;
> > >
> > > This function back in UMS used to be about getting the system from
> > > unknown bootup state to other junk being turned off after the initial
> > > modeset (which was of course broken, since having the other junk turned
> > > on during modeset could break things, so really it should have been
> > > intel_turn_everything_off_thanks() before doing a modeset).
> > >
> > > Once that's fixed, it seems like it'd be a replacement for the
> > > turn-off-after-load-detect logic in the load detect pipe release
> > > function.
> > >   
> > 
> > Did anything get applied to fix this issue in the end ? Jesse's initial
> > patch fixed blank screens on my i 945 so I am still applying it to my
> > kernels for now.
> 
> Arg, totally dropped this one.
> 
> Dave, please comment on the above.

I take that back; this shouldn't be required now that we
unconditionally return connected from the LVDS detect hook.

Brice, are you seeing something different?  I.e. is this patch required
for you even on current kernels?

-- 
Jesse Barnes, Intel Open Source Technology Center