[Intel-gfx] [PATCH] drm/i915: Only poll DW3_A when init DDI PHY for ports B and C.

[Imre Deak]

On ma, 2016-11-14 at 21:51 +0200, Vivi, Rodrigo wrote:
> On Fri, 2016-11-11 at 15:09 +0200, Imre Deak wrote:
> > On to, 2016-11-10 at 17:03 -0800, Rodrigo Vivi wrote:
> > > According to Bspec we need to
> > > "Poll for PORT_REF_DW3_A grc_done == 1b"
> > > only on ports B and C initialization sequence when
> > > copying rcomp from port A.
> > > 
> > > So let's follow the spec and only poll for that case
> > > and not on every port A initialization.
> > > 
> > > Cc: Imre Deak <imre.deak at intel.com>
> > > Cc: Ander Conselvan de Oliveira 
> > > Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> > 
> > The current code isn't against the spec, we just wait for the
> > calibration to complete earlier. This way we also wait in case only
> > port A is enabled which is imo safer to do before a subsequent
> > modeset
> > on port A. But yes, the spec suggests the HW will handle the wait
> > for
> > this - only port A - case internally, so we can move the wait later
> > to
> > reduce somewhat the init time:
> > 
> > Reviewed-by: Imre Deak <imre.deak at intel.com>
> 
> Ops, actually I noticed later that I need to remove the warning block
> with return false from is_phy_enabled if grc isn't done. otherwise it
> will force a reprograming without this line there.

Yea, missed that too.

> 
> So, do you believe it is worth to do a v2 removing that block or
> better
> to just ignore this patch?

The calibration takes ~2ms on my APL, so I think it's worth reducing
that delay.

> 
> > 
> > > ---
> > >  drivers/gpu/drm/i915/intel_dpio_phy.c | 7 +++----
> > >  1 file changed, 3 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_dpio_phy.c
> > > b/drivers/gpu/drm/i915/intel_dpio_phy.c
> > > index 7a8e82d..277b1aa 100644
> > > --- a/drivers/gpu/drm/i915/intel_dpio_phy.c
> > > +++ b/drivers/gpu/drm/i915/intel_dpio_phy.c
> > > @@ -367,6 +367,9 @@ static void _bxt_ddi_phy_init(struct
> > > drm_i915_private *dev_priv,
> > >  
> > >  	if (phy_info->rcomp_phy != -1) {
> > >  		uint32_t grc_code;
> > > +
> > > +		bxt_phy_wait_grc_done(dev_priv, phy_info-
> > > >rcomp_phy);
> > > +
> > >  		/*
> > >  		 * PHY0 isn't connected to an RCOMP resistor so
> > > copy over
> > >  		 * the corresponding calibrated value from PHY1,
> > > and disable
> > > @@ -387,10 +390,6 @@ static void _bxt_ddi_phy_init(struct
> > > drm_i915_private *dev_priv,
> > >  	val = I915_READ(BXT_PHY_CTL_FAMILY(phy));
> > >  	val |= COMMON_RESET_DIS;
> > >  	I915_WRITE(BXT_PHY_CTL_FAMILY(phy), val);
> > > -
> > > -	if (phy_info->rcomp_phy == -1)
> > > -		bxt_phy_wait_grc_done(dev_priv, phy);
> > > -
> > >  }
> > >  
> > >  void bxt_ddi_phy_uninit(struct drm_i915_private *dev_priv, enum
> > > dpio_phy phy)
>