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

[Jani Nikula <jani.nikula@intel.com>]

On Tue, 05 Oct 2021, "Souza, Jose" <jose.souza@intel.com> wrote:
> On Tue, 2021-10-05 at 23:38 +0300, Jani Nikula wrote:
>> On Tue, 05 Oct 2021, "Souza, Jose" <jose.souza@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@intel.com>
>> > > Cc: Uma Shankar <uma.shankar@intel.com>
>> > > Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
>> > > Cc: Swati Sharma <swati2.sharma@intel.com>
>> > > Signed-off-by: Jani Nikula <jani.nikula@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@intel.com>

Thanks, pushed with Swati's Tested-by.

BR,
Jani.


>
>> 
>> 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);
>> > >  
>> > 
>> 
>

-- 
Jani Nikula, Intel Open Source Graphics Center