[Intel-gfx] 3.14.3 i915 dead display under X11

[Daniel Vetter]

On Wed, May 14, 2014 at 03:43:53PM -0400, Josh Boyer wrote:
> On Wed, May 14, 2014 at 3:33 PM, Greg KH <gregkh at linuxfoundation.org> wrote:
> > On Wed, May 14, 2014 at 09:19:32PM +0200, Daniel Vetter wrote:
> >> On Wed, May 14, 2014 at 08:47:38PM +0200, Bruno Prémont wrote:
> >> > CCing intel-gfx as otherwise it will probably not get seen by developers.
> >> >
> >> > On Sun, 11 May 2014 Carbonated Beverage <ramune at psychosnugglebunnies.net> wrote:
> >> > > Bisecting from 3.13.6 (good) to 3.14.3 (bad) ended up with...
> >> > >
> >> > > commit b35684b8fa94e04f55fd38bf672b737741d2f9e2
> >> > > Author: Jani Nikula <jani.nikula at intel.com>
> >> > > Date:   Thu Nov 14 12:13:41 2013 +0200
> >> > >
> >> > >     drm/i915: do full backlight setup at enable time
> >> > >
> >> > >     We should now have all the information we need to do a full
> >> > >     initialization of the backlight registers.
> >> > >
> >> > >     v2: Keep QUIRK_NO_PCH_PWM_ENABLE for now (Imre).
> >> > >
> >> > >     Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> >> > >     Reviewed-by: Imre Deak <imre.deak at intel.com>
> >> > >     Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> >> > >
> >> > > Which is in 3.12.0????
> >> > >
> >> > > I'm not sure how that came to be.  Does that look right?  What other
> >> > > information would be required to track this down?
> >>
> >> We've killed this again in 3.14 since we've hoped the backlight rework in
> >> there fixed it. For 3.15 we finally have the right fix - vbt has a bit
> >> telling us not to look at the integrated PWM for the panel.
> >>
> >> For 3.14 we will (again) resurrect the quirk because the vbt thing is a
> >> bit too risky an imo needs a full -rc cycle for testing. But that revert
> >> is currently stalled because Greg KH is travelling too much ;-)
> >>
> >> Cc'ing him to make sure that patch doesn't miss the next 3.14.x release.
> >
> > What specific patch are you wanting to make sure makes it in?  I've been
> 
> Subject: [PATCH for stable 3.14 only 0/1] drm/i915: restore
> QUIRK_NO_PCH_PWM_ENABLE

Yep, that's the one. Jani's mail has a detailed explanation of the
hilarity we've pulled off this time around.

> > avoiding all of the drm patches so far for 3.14.y as it's an easy thing
> > to do, but I'll eventually have to start paying attention to them :)

Hey, you've praised me at fosdem how good a job we do with tagging cc:
stable, you need to keep up your end of the bargain too ;-)

> Jani has bugged you twice about it I think.  You've said it's not lost
> both times.  Third time is a charm?

Cheers, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch