Re: [PATCH 7/6] drm/i915/skl: DDI-E and DDI-A shares 4 lanes.

["Vivi, Rodrigo" <rodrigo.vivi@intel.com>]

On Tue, 2015-08-11 at 07:05 +0000, Zhang, Xiong Y wrote:
> > -----Original Message-----
> > From: Vivi, Rodrigo
> > Sent: Saturday, August 8, 2015 8:34 AM
> > To: intel-gfx@lists.freedesktop.org
> > Cc: Vivi, Rodrigo; Zhang, Xiong Y
> > Subject: [PATCH 7/6] drm/i915/skl: DDI-E and DDI-A shares 4 lanes.
> > 
> > DDI-A and DDI-E shares the 4 lanes. So when DDI-E is present we 
> > need to
> > configure lane count propperly for both.
> > 
> > This was based on Sonika's
> > [PATCH] drm/i915/skl: Select DDIA lane capability based upon vbt
> > 
> > Credits-to: Sonika Jindal <sonika.jindal@intel.com>
> > Cc: Xiong Zhang <xiong.y.zhang@intel.com>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_ddi.c | 12 ++++++++++--
> > drivers/gpu/drm/i915/intel_dp.c  |  8 +++++---
> >  2 files changed, 15 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c
> > b/drivers/gpu/drm/i915/intel_ddi.c
> > index 110d546..557cecf 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -3178,7 +3178,15 @@ void intel_ddi_init(struct drm_device *dev, 
> > enum
> > port port)
> >  	struct intel_digital_port *intel_dig_port;
> >  	struct intel_encoder *intel_encoder;
> >  	struct drm_encoder *encoder;
> > -	bool init_hdmi, init_dp;
> > +	bool init_hdmi, init_dp, ddi_e_present;
> > +
> > +	/*
> > +	 * On SKL we don't have a way to detect DDI-E so we rely 
> > on VBT.
> > +	 */
> > +	ddie_present = IS_SKYLAKE(dev) &&
> > +		(dev_priv->vbt.ddi_port_info[PORT_E].supports_dp 
> > ||
> > +		 dev_priv->vbt.ddi_port_info[PORT_E].supports_dvi 
> > ||
> > +		 dev_priv
> > ->vbt.ddi_port_info[PORT_E].supports_hdmi);
> [Zhang, Xiong Y]  ddie_present should be ddi_e_present
> > 
> >  	init_hdmi = (dev_priv
> > ->vbt.ddi_port_info[port].supports_dvi ||
> >  		     dev_priv
> > ->vbt.ddi_port_info[port].supports_hdmi);
> > @@ -3210,7 +3218,7 @@ void intel_ddi_init(struct drm_device *dev, 
> > enum
> > port port)
> >  	intel_dig_port->port = port;
> >  	intel_dig_port->saved_port_bits = 
> > I915_READ(DDI_BUF_CTL(port)) &
> >  					  (DDI_BUF_PORT_REVERSAL |
> > -					   DDI_A_4_LANES);
> > +					   ddi_e_present ? 0 : 
> > DDI_A_4_LANES);
> [Zhang, Xiong Y] Sonika's patch will set DDI-A to 4 lanes when DDI-E 
> doesn't exist,
> I think your patch will do nothing.

Actually DDI_A_4_LANES is being already set unconditionally, so
Sonika's patch has no effect.

saved_port_bits goes to intel_dp->DP that goes to DDI_BUF_CTL and also
it is used to calculate the number of lanes.

With this patch we stop setting DDI_A_4_LANES when ddi_e is present so
DDI-A keeps with 2 lanes and let other 2 lanes for DDI-E

> > 
> >  	intel_encoder->type = INTEL_OUTPUT_UNKNOWN;
> >  	intel_encoder->crtc_mask = (1 << 0) | (1 << 1) | (1 << 2); 
> > diff --git
> > a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c 
> > index
> > 3ff2080..7ada79e 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -159,9 +159,11 @@ static u8 intel_dp_max_lane_count(struct 
> > intel_dp
> > *intel_dp)
> >  	u8 source_max, sink_max;
> > 
> >  	source_max = 4;
> > -	if (HAS_DDI(dev) && intel_dig_port->port == PORT_A &&
> > -	    (intel_dig_port->saved_port_bits & DDI_A_4_LANES) == 
> > 0)
> > -		source_max = 2;
> > +	if (HAS_DDI(dev) && (intel_dig_port->port == PORT_E ||
> > +			     (intel_dig_port->port == PORT_A &&
> > +			      (intel_dig_port->saved_port_bits &
> > +			       DDI_A_4_LANES) == 0))
> > +	    source_max = 2;
> [Zhang, Xiong Y] it miss ')' at the end line. 
> > 
> >  	sink_max = drm_dp_max_lane_count(intel_dp->dpcd);
> > 
> > --
> > 2.4.3
> 
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