Re: [PATCH 03/31] drm/i915: lock down pch pll accouting some more

[Daniel Vetter <daniel@ffwll.ch>]

On Fri, Jun 07, 2013 at 11:46:08PM +0300, Ville Syrjälä wrote:
> On Fri, Jun 07, 2013 at 10:03:20PM +0200, Daniel Vetter wrote:
> > On Fri, Jun 07, 2013 at 07:32:56PM +0300, Ville Syrjälä wrote:
> > > On Wed, Jun 05, 2013 at 01:34:05PM +0200, Daniel Vetter wrote:
> > > > Before I start to make a complete mess out of this, crank up
> > > > the paranoia level a bit.
> > > > 
> > > > Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > > > ---
> > > >  drivers/gpu/drm/i915/intel_display.c | 9 ++++++++-
> > > >  1 file changed, 8 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > > index 56fb6ed..39e977f 100644
> > > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > > @@ -1440,6 +1440,7 @@ static void intel_disable_pch_pll(struct intel_crtc *intel_crtc)
> > > >  	}
> > > >  
> > > >  	assert_pch_pll_enabled(dev_priv, pll, NULL);
> > > > +	WARN_ON(!pll->on);
> > > >  	if (--pll->active)
> > > >  		return;
> > > 
> > > Maybe a WARN_ON(pll->on) near the end of ironlake_enable_pch_pll() too?
> > 
> > At the very end we set on = true, and the only non-error early return
> > (when the active refcount is > 0 to begin with) has alreay a
> > WARN_ON(!pll->on). Shouldn't that be good enough?
> 
> Well I was just thinking that since we have this dual bookeeping w/
> active and on, maybe we want to warn if things go out of sync.

Now I'm confused. I've tried to explain why I think we already have full
checking of pll->on in enable_shared_dpll ... Can you maybe show in a diff
where you'd want to add more?
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch