Re: [PATCH 3/5] drm/i915/icl: Update FIA supported lane count for hpd.

From: Rodrigo Vivi <rodrigo.vivi@intel.com>
To: Paulo Zanoni <paulo.r.zanoni@intel.com>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 3/5] drm/i915/icl: Update FIA supported lane count for hpd.
Date: Wed, 25 Jul 2018 10:13:54 -0700	[thread overview]
Message-ID: <20180725171354.GN16907@intel.com> (raw)
In-Reply-To: <20180725165225.GJ16907@intel.com>

On Wed, Jul 25, 2018 at 09:52:25AM -0700, Rodrigo Vivi wrote:
> On Tue, Jul 24, 2018 at 05:28:11PM -0700, Paulo Zanoni wrote:
> > From: Animesh Manna <animesh.manna@intel.com>
> > 
> > In ICL, Flexible IO Adapter (FIA) muxes data and clocks of USB 3.1,
> > tbt and display controller. In DP alt mode FIA configure the
> > number of lanes and will be used apart from DPCD read to calculate max
> > available lanes for DP enablement.
> > 
> > v2 (from Paulo): Simple rebase.
> > 
> > Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com> (v1).
> > Signed-off-by: Animesh Manna <animesh.manna@intel.com>
> > [Paulo: significant rewrite of the patch.]
> > Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_reg.h |  3 +++
> >  drivers/gpu/drm/i915/intel_dp.c | 33 ++++++++++++++++++++++++++++++++-
> >  2 files changed, 35 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> > index 93de6f724e77..72acecaad5c1 100644
> > --- a/drivers/gpu/drm/i915/i915_reg.h
> > +++ b/drivers/gpu/drm/i915/i915_reg.h
> > @@ -10705,5 +10705,8 @@ enum skl_power_gate {
> >  #define PORT_TX_DFLEXDPSP			_MMIO(0x1638A0)
> >  #define   TC_LIVE_STATE_TBT(tc_port)		(1 << ((tc_port) * 8 + 6))
> >  #define   TC_LIVE_STATE_TC(tc_port)		(1 << ((tc_port) * 8 + 5))
> > +#define   DP_LANE_ASSIGNMENT_SHIFT(tc_port)	((tc_port) * 8)
> > +#define   DP_LANE_ASSIGNMENT_MASK(tc_port)	(0xf << ((tc_port) * 8))
> > +#define   DP_LANE_ASSIGNMENT(tc_port, x)	((x) << ((tc_port) * 8))
> >  
> >  #endif /* _I915_REG_H_ */
> > diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> > index 90c5ba6b222b..bb59e71d6f9c 100644
> > --- a/drivers/gpu/drm/i915/intel_dp.c
> > +++ b/drivers/gpu/drm/i915/intel_dp.c
> > @@ -176,14 +176,45 @@ static int intel_dp_max_common_rate(struct intel_dp *intel_dp)
> >  	return intel_dp->common_rates[intel_dp->num_common_rates - 1];
> >  }
> >  
> > +static int intel_dp_get_fia_supported_lane_count(struct intel_dp *intel_dp)
> > +{
> > +	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
> > +	struct drm_i915_private *dev_priv = to_i915(dig_port->base.base.dev);
> > +	enum tc_port tc_port = intel_port_to_tc(dev_priv, dig_port->base.port);
> > +	u32 lane_info;
> > +
> > +	if (tc_port == PORT_TC_NONE || dig_port->tc_type != TC_PORT_TYPEC)
> > +		return 4;
> > +
> > +	lane_info = (I915_READ(PORT_TX_DFLEXDPSP) &
> > +		     DP_LANE_ASSIGNMENT_MASK(tc_port)) >>
> > +		    DP_LANE_ASSIGNMENT_SHIFT(tc_port);
> > +
> > +	switch (lane_info) {
> > +	default:
> > +		MISSING_CASE(lane_info);
> > +	case 1:
> > +	case 2:
> > +	case 4:
> > +	case 8:
> > +		return 1;
> > +	case 3:
> > +	case 12:
> > +		return 2;
> > +	case 15:
> > +		return 4;
> 
> what about replacing this entire switch per a simple
> 
> return hweight8(lane_info);

ignore this.
specially considering that SOC FW sets these bits, not HW,
I agree that MISSING_CASE is very important.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> 
> ?
> 
> > +	}
> > +}
> > +
> >  /* Theoretical max between source and sink */
> >  static int intel_dp_max_common_lane_count(struct intel_dp *intel_dp)
> >  {
> >  	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> >  	int source_max = intel_dig_port->max_lanes;
> >  	int sink_max = drm_dp_max_lane_count(intel_dp->dpcd);
> > +	int fia_max = intel_dp_get_fia_supported_lane_count(intel_dp);
> >  
> > -	return min(source_max, sink_max);
> > +	return min3(source_max, sink_max, fia_max);
> >  }
> >  
> >  int intel_dp_max_lane_count(struct intel_dp *intel_dp)
> > -- 
> > 2.17.1
> > 
> > _______________________________________________
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> > Intel-gfx@lists.freedesktop.org
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