[Intel-gfx] [PATCH] drm/i915: disable_shared_pll doesn't work on pre-gen5

[Chris Wilson]

On Tue, Aug 11, 2015 at 11:30:48AM +0200, Daniel Vetter wrote:
> On Mon, Aug 10, 2015 at 11:15:30AM +0100, Chris Wilson wrote:
> > On Mon, Aug 03, 2015 at 01:09:11PM -0700, Jesse Barnes wrote:
> > > Looks like
> > > 
> > > commit eddfcbcdc27fbecb33bff098967bbdd7ca75bfa6
> > > Author: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > > Date:   Mon Jun 15 12:33:53 2015 +0200
> > >     drm/i915: Update less state during modeset.
> > > 
> > > introduced the unconditional calling of disable_shared_dpll, but didn't
> > > fix up pre-gen5 to avoid the BUG_ON at the top of the function.
> > > 
> > > So change the BUG_ON into a gen check (alternately we could move the
> > > BUG_ON until later, since we shouldn't have a pll struct here either,
> > > but this seems clearer to read).
> > > 
> > > This fixes a crash on load on my x200s platform.
> > > 
> > > Signed-off-by: Jesse Barnes <jbarnes at virtuousgeek.org>
> > 
> > This blows up in 4.1 (a BUG_ON during boot causing a hard lockup).
> 
> The reference offending commit is 4.3 only. Are you sure it's the same
> BUG_ON? Which machine?

It's entirely probably that I messed up my bisect, something about
compiling a kernel a day for a couple of weeks and forgetting which step
it is at...
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre