On Tue, Oct 24, 2017 at 09:21:38AM +0000, Ville Syrjälä wrote:
> On Mon, Oct 23, 2017 at 10:39:20AM -0700, Rodrigo Vivi wrote:
> > As we faced in BXT, on CNL DDI_A_4_LANES is not
> > set as expected when system is boot with multiple
> > monitors connected. This result in wrong lane
> > setup impacting the max data rate available and
> > consequently blocking modeset on eDP, resulting
> > in a blank screen.
> >
> > Most of CNL SKUs don't support DDI-E.
> > The only SKU that supports DDI-E is the same
> > that supports the full A/E split called DDI-F.
> >
> > Also when DDI-F is used DDI-E cannot be used because
> > they share Interrupts. So DDI-E is almost useless.
> > Anyways let's consider this is possible and rely on
> > VBT for that.
> >
> > This patch was initialy start by Clint, but required
> > many changes including full commit message. So
> > Credits entirely to Clint for finding this.
> >
> > v2: Extract all messy conditions into a helper function
> > as suggested by Ville.
> > Along with simplification I removed the debug
> > message on the working case since now all conditions
> > are grouped.
> > v3: Split the conditions even more as suggested by Ville.
> > Get's cleaner and easier to add new cases in the
> > future.
> >
> > Suggested-by: Clint Taylor <clinton.a.taylor@xxxxxxxxx>
> > Cc: Clint Taylor <clinton.a.taylor@xxxxxxxxx>
> > Cc: Mika Kahola <mika.kahola@xxxxxxxxx>
> > Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>
> Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Thanks for review and all great suggestions.
Merged to dinq.
>
> > ---
> > drivers/gpu/drm/i915/intel_ddi.c | 46 ++++++++++++++++++++++++++++++----------
> > 1 file changed, 35 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> > index adf51b328844..38a7088bd39c 100644
> > --- a/drivers/gpu/drm/i915/intel_ddi.c
> > +++ b/drivers/gpu/drm/i915/intel_ddi.c
> > @@ -2694,6 +2694,34 @@ intel_ddi_init_hdmi_connector(struct intel_digital_port *intel_dig_port)
> > return connector;
> > }
> >
> > +static bool intel_ddi_a_force_4_lanes(struct intel_digital_port *dport)
> > +{
> > + struct drm_i915_private *dev_priv = to_i915(dport->base.base.dev);
> > +
> > + if (dport->port != PORT_A)
> > + return false;
> > +
> > + if (dport->saved_port_bits & DDI_A_4_LANES)
> > + return false;
> > +
> > + /* Broxton/Geminilake: Bspec says that DDI_A_4_LANES is the only
> > + * supported configuration
> > + */
> > + if (IS_GEN9_LP(dev_priv))
> > + return true;
> > +
> > + /* Cannonlake: Most of SKUs don't support DDI_E, and the only
> > + * one who does also have a full A/E split called
> > + * DDI_F what makes DDI_E useless. However for this
> > + * case let's trust VBT info.
> > + */
> > + if (IS_CANNONLAKE(dev_priv) &&
> > + !intel_bios_is_port_present(dev_priv, PORT_E))
> > + return true;
> > +
> > + return false;
> > +}
> > +
> > void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
> > {
> > struct intel_digital_port *intel_dig_port;
> > @@ -2803,18 +2831,14 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
> > }
> >
> > /*
> > - * Bspec says that DDI_A_4_LANES is the only supported configuration
> > - * for Broxton. Yet some BIOS fail to set this bit on port A if eDP
> > - * wasn't lit up at boot. Force this bit on in our internal
> > - * configuration so that we use the proper lane count for our
> > - * calculations.
> > + * Some BIOS might fail to set this bit on port A if eDP
> > + * wasn't lit up at boot. Force this bit set when needed
> > + * so we use the proper lane count for our calculations.
> > */
> > - if (IS_GEN9_LP(dev_priv) && port == PORT_A) {
> > - if (!(intel_dig_port->saved_port_bits & DDI_A_4_LANES)) {
> > - DRM_DEBUG_KMS("BXT BIOS forgot to set DDI_A_4_LANES for port A; fixing\n");
> > - intel_dig_port->saved_port_bits |= DDI_A_4_LANES;
> > - max_lanes = 4;
> > - }
> > + if (intel_ddi_a_force_4_lanes(intel_dig_port)) {
> > + DRM_DEBUG_KMS("Forcing DDI_A_4_LANES for port A\n");
> > + intel_dig_port->saved_port_bits |= DDI_A_4_LANES;
> > + max_lanes = 4;
> > }
> >
> > intel_dig_port->max_lanes = max_lanes;
> > --
> > 2.13.5
>
> --
> Ville Syrjälä
> Intel OTC
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