[Intel-gfx] [PATCH 2/2] drm/i915/glk: Fix DMC/DC state idleness calculation

[Rodrigo Vivi]

On Tue, Oct 03, 2017 at 05:47:50PM +0000, Rodrigo Vivi wrote:
> On Tue, Oct 03, 2017 at 09:51:59AM +0000, Imre Deak wrote:
> > According to BSpec GLK like BXT needs to ignore the idle state of cores
> > before starting the DMC firmware's DC state handler.
> 
> no mention on CNL there?
> 
> Btw I just saw that CNL DMC seems much more like BXT than like SKL.
> Our code probably needs deeper changes...

nevermind. I was wrong about this.
The only difference I see on CNL compared with SKL now
is the bit 31 of DC_STATE_EN...

A bit that we should set during modeset and clear after. But there is
no mention about that bit on the main sequences page and also we
leave dc states disabled during modeset anyways besides that
clock gating wa... So I believe we are safe.

Imre, thoughts?

> 
> > 
> > Fixes: dbb28b5c3d3c ("drm/i915/DMC/GLK: Load DMC on GLK")
> > Cc: Anusha Srivatsa <anusha.srivatsa at intel.com>
> > Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_csr.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
> > index cdfb624eb82d..ea5d5c9645a4 100644
> > --- a/drivers/gpu/drm/i915/intel_csr.c
> > +++ b/drivers/gpu/drm/i915/intel_csr.c
> > @@ -216,7 +216,7 @@ static void gen9_set_dc_state_debugmask(struct drm_i915_private *dev_priv)
> >  
> >  	mask = DC_STATE_DEBUG_MASK_MEMORY_UP;
> >  
> > -	if (IS_BROXTON(dev_priv))
> > +	if (IS_GEN9_LP(dev_priv))
> >  		mask |= DC_STATE_DEBUG_MASK_CORES;
> 
> I saw in spec for SKL+: "This field must be set to Mask prior to enabling DC5 or DC6"
> So I believe this should be INTEL_GEN(dev_priv) >= 9... :/
> 
> 
> >  
> >  	/* The below bit doesn't need to be cleared ever afterwards */
> > -- 
> > 2.13.2
> >