[Intel-gfx] [PATCH] drm/i915/bios: gracefully disable dual eDP for now

[Souza, Jose]

On Tue, 2021-10-05 at 23:38 +0300, Jani Nikula wrote:
> On Tue, 05 Oct 2021, "Souza, Jose" <jose.souza at intel.com> wrote:
> > On Tue, 2021-10-05 at 20:56 +0300, Jani Nikula wrote:
> > > For the time being, neither the power sequencer nor the backlight code
> > > properly support two eDP panels simultaneously. While the software
> > > states will be independent, the same sets of registers will be used for
> > > both eDP panels, clobbering the hardware state and leading to errors.
> > > 
> > > Gracefully disable dual eDP until proper support has been added.
> > > 
> > > Cc: José Roberto de Souza <jose.souza at intel.com>
> > > Cc: Uma Shankar <uma.shankar at intel.com>
> > > Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > Cc: Swati Sharma <swati2.sharma at intel.com>
> > > Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_bios.c | 47 +++++++++++++++++++++++
> > >  1 file changed, 47 insertions(+)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> > > index f9776ca85de3..b99907c656bb 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_bios.c
> > > +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> > > @@ -1930,6 +1930,50 @@ static int _intel_bios_max_tmds_clock(const struct intel_bios_encoder_data *devd
> > >  	}
> > >  }
> > >  
> > > +static enum port get_edp_port(struct drm_i915_private *i915)
> > > +{
> > > +	const struct intel_bios_encoder_data *devdata;
> > > +	enum port port;
> > > +
> > > +	for_each_port(port) {
> > > +		devdata = i915->vbt.ports[port];
> > > +
> > > +		if (devdata && intel_bios_encoder_supports_edp(devdata))
> > > +			return port;
> > > +	}
> > > +
> > > +	return PORT_NONE;
> > > +}
> > > +
> > > +/*
> > > + * FIXME: The power sequencer and backlight code currently do not support more
> > > + * than one set registers, at least not on anything other than VLV/CHV. It will
> > > + * clobber the registers. As a temporary workaround, gracefully prevent more
> > > + * than one eDP from being registered.
> > > + */
> > > +static void sanitize_dual_edp(struct intel_bios_encoder_data *devdata,
> > > +			      enum port port)
> > > +{
> > > +	struct drm_i915_private *i915 = devdata->i915;
> > > +	struct child_device_config *child = &devdata->child;
> > > +	enum port p;
> > > +
> > > +	/* CHV might not clobber PPS registers. */
> > > +	if (IS_CHERRYVIEW(i915))
> > > +		return;
> > > +
> > > +	p = get_edp_port(i915);
> > > +	if (p == PORT_NONE)
> > > +		return;
> > > +
> > > +	drm_dbg_kms(&i915->drm, "both ports %c and %c configured as eDP, "
> > > +		    "disabling port %c eDP\n", port_name(p), port_name(port),
> > > +		    port_name(port));
> > > +
> > > +	child->device_type &= ~DEVICE_TYPE_DISPLAYPORT_OUTPUT;
> > 
> > Why also cleaning the DEVICE_TYPE_DISPLAYPORT_OUTPUT bit? The rest lgtm.
> 
> Could've leaned one way or the other, but do we really want to
> initialize a regular DP on the port?

Yeah, lets go without.

Reviewed-by: José Roberto de Souza <jose.souza at intel.com>

> 
> BR,
> Jani.
> 
> > 
> > > +	child->device_type &= ~DEVICE_TYPE_INTERNAL_CONNECTOR;
> > > +}
> > > +
> > >  static bool is_port_valid(struct drm_i915_private *i915, enum port port)
> > >  {
> > >  	/*
> > > @@ -1987,6 +2031,9 @@ static void parse_ddi_port(struct drm_i915_private *i915,
> > >  		    supports_typec_usb, supports_tbt,
> > >  		    devdata->dsc != NULL);
> > >  
> > > +	if (is_edp)
> > > +		sanitize_dual_edp(devdata, port);
> > > +
> > >  	if (is_dvi)
> > >  		sanitize_ddc_pin(devdata, port);
> > >  
> > 
>