Re: [PATCH v4 02/11] drm/i915/vbt: Add fields dedicated_external and dyn_port_over_tc

[Imre Deak <imre.deak@intel.com>]

On Tue, Nov 11, 2025 at 06:02:31PM +0200, Imre Deak wrote:
> On Fri, Nov 07, 2025 at 09:05:35PM -0300, Gustavo Sousa wrote:
> > VBT version 264 adds new fields associated to Xe3p_LPD's new ways of
> > configuring SoC for TC ports and PHYs.  Update the code to match the
> > updates in VBT.
> > 
> > The new field dedicated_external is used to represent TC ports that are
> > connected to PHYs outside of the Type-C subsystem, meaning that they
> > behave like dedicated ports and don't require the extra Type-C
> > programming.  In an upcoming change, we will update the driver to take
> > this field into consideration when detecting the type of port.
> > 
> > The new field dyn_port_over_tc is used to inform that the TC port can be
> > dynamically allocated for a legacy connector in the Type-C subsystem,
> > which is a new feature in Xe3p_LPD.  In upcoming changes, we will use
> > that field in order to handle the IOM resource management programming
> > required for that.
> > 
> > Note that, when dedicated_external is set, the fields dp_usb_type_c and
> > tbt are tagged as "don't care" in the spec, so they should be ignored in
> > that case, so also add a sanitization function to take care of forcing
> > them to zero when dedicated_external is true.
> > 
> > v2:
> >   - Use sanitization function to force dp_usb_type_c and tbt fields to
> >     be zero instead of adding a
> >     intel_bios_encoder_is_dedicated_external() check in each of their
> >     respective accessor functions. (Jani)
> >   - Print info about dedicated external ports in print_ddi_port().
> >     (Jani)
> > 
> > Bspec: 20124, 68954, 74304
> > Cc: Jani Nikula <jani.nikula@linux.intel.com>
> > Cc: Shekhar Chauhan <shekhar.chauhan@intel.com>
> > Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_bios.c     | 54 ++++++++++++++++++++++++++-
> >  drivers/gpu/drm/i915/display/intel_bios.h     |  2 +
> >  drivers/gpu/drm/i915/display/intel_vbt_defs.h |  3 +-
> >  3 files changed, 56 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> > index 852e4d6db8a3..1487d5e5a69d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_bios.c
> > +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> > @@ -2530,6 +2530,36 @@ intel_bios_encoder_reject_edp_rate(const struct intel_bios_encoder_data *devdata
> >  	return devdata->child.edp_data_rate_override & edp_rate_override_mask(rate);
> >  }
> >  
> > +static void sanitize_dedicated_external(struct intel_bios_encoder_data *devdata,
> > +					enum port port)
> > +{
> > +	struct intel_display *display = devdata->display;
> > +
> > +	if (!intel_bios_encoder_is_dedicated_external(devdata))
> > +		return;
> > +
> > +	/*
> > +	 * Fields dp_usb_type_c and tbt must be ignored when
> > +	 * dedicated_external is set.  Since dedicated_external is for
> > +	 * ports connected to PHYs outside of the Type-C subsystem, it
> > +	 * is safe to force those fields to zero.
> > +	 */

Forgot this: IIUC dyn_port_over_tc doesn't make either sense for a
dedicated external port. IOW, a dedicated port/PHY is not enabled by the
TypeC sequences defined at bspec/68954 and so for such a port/PHY the
DDI->PHY mapping is always 1:1 and so the corresponding DDI can't either
be dynamically allocated to different PHYs. If that's a correct
understanding, dyn_port_over_tc should be also verified/zeroed out here
imo.

> > +
> > +	if (devdata->child.dp_usb_type_c) {
> > +		drm_dbg_kms(display->drm,
> > +			    "VBT claims Port %c supports USB Type-C, but the port is dedicated external, ignoring\n",
> > +			    port_name(port));
> > +		devdata->child.dp_usb_type_c = 0;
> > +	}
> > +
> > +	if (devdata->child.tbt) {
> > +		drm_dbg_kms(display->drm,
> > +			    "VBT claims Port %c supports TBT, but the port is dedicated external, ignoring\n",
> > +			    port_name(port));
> > +		devdata->child.tbt = 0;
> > +	}
> > +}
> > +
> >  static void sanitize_device_type(struct intel_bios_encoder_data *devdata,
> >  				 enum port port)
> >  {
> > @@ -2668,7 +2698,8 @@ static void print_ddi_port(const struct intel_bios_encoder_data *devdata)
> >  {
> >  	struct intel_display *display = devdata->display;
> >  	const struct child_device_config *child = &devdata->child;
> > -	bool is_dvi, is_hdmi, is_dp, is_edp, is_dsi, is_crt, supports_typec_usb, supports_tbt;
> > +	bool is_dvi, is_hdmi, is_dp, is_edp, is_dsi, is_crt, supports_typec_usb,
> > +		supports_tbt, dedicated_external;
> >  	int dp_boost_level, dp_max_link_rate, hdmi_boost_level, hdmi_level_shift, max_tmds_clock;
> >  	enum port port;
> >  
> > @@ -2694,6 +2725,12 @@ static void print_ddi_port(const struct intel_bios_encoder_data *devdata)
> >  		    supports_typec_usb, supports_tbt,
> >  		    devdata->dsc != NULL);
> >  
> > +	dedicated_external = intel_bios_encoder_is_dedicated_external(devdata);
> > +	if (dedicated_external)
> 
> Nit: the variable could be dropped imo, and would be good to print the
> dyn_port_over_tc info as well. Either way:
> 
> Reviewed-by: Imre Deak <imre.deak@intel.com>
> 
> > +		drm_dbg_kms(display->drm,
> > +			    "Port %c is dedicated external\n",
> > +			    port_name(port));
> > +
> >  	hdmi_level_shift = intel_bios_hdmi_level_shift(devdata);
> >  	if (hdmi_level_shift >= 0) {
> >  		drm_dbg_kms(display->drm,
> > @@ -2751,6 +2788,7 @@ static void parse_ddi_port(struct intel_bios_encoder_data *devdata)
> >  		return;
> >  	}
> >  
> > +	sanitize_dedicated_external(devdata, port);
> >  	sanitize_device_type(devdata, port);
> >  	sanitize_hdmi_level_shift(devdata, port);
> >  }
> > @@ -2778,7 +2816,7 @@ static int child_device_expected_size(u16 version)
> >  {
> >  	BUILD_BUG_ON(sizeof(struct child_device_config) < 40);
> >  
> > -	if (version > 263)
> > +	if (version > 264)
> >  		return -ENOENT;
> >  	else if (version >= 263)
> >  		return 44;
> > @@ -3723,6 +3761,18 @@ bool intel_bios_encoder_supports_tbt(const struct intel_bios_encoder_data *devda
> >  	return devdata->display->vbt.version >= 209 && devdata->child.tbt;
> >  }
> >  
> > +bool intel_bios_encoder_is_dedicated_external(const struct intel_bios_encoder_data *devdata)
> > +{
> > +	return devdata->display->vbt.version >= 264 &&
> > +		devdata->child.dedicated_external;
> > +}
> > +
> > +bool intel_bios_encoder_supports_dyn_port_over_tc(const struct intel_bios_encoder_data *devdata)
> > +{
> > +	return devdata->display->vbt.version >= 264 &&
> > +		devdata->child.dyn_port_over_tc;
> > +}
> > +
> >  bool intel_bios_encoder_lane_reversal(const struct intel_bios_encoder_data *devdata)
> >  {
> >  	return devdata && devdata->child.lane_reversal;
> > diff --git a/drivers/gpu/drm/i915/display/intel_bios.h b/drivers/gpu/drm/i915/display/intel_bios.h
> > index f9e438b2787b..75dff27b4228 100644
> > --- a/drivers/gpu/drm/i915/display/intel_bios.h
> > +++ b/drivers/gpu/drm/i915/display/intel_bios.h
> > @@ -79,6 +79,8 @@ bool intel_bios_encoder_supports_dp(const struct intel_bios_encoder_data *devdat
> >  bool intel_bios_encoder_supports_edp(const struct intel_bios_encoder_data *devdata);
> >  bool intel_bios_encoder_supports_typec_usb(const struct intel_bios_encoder_data *devdata);
> >  bool intel_bios_encoder_supports_tbt(const struct intel_bios_encoder_data *devdata);
> > +bool intel_bios_encoder_is_dedicated_external(const struct intel_bios_encoder_data *devdata);
> > +bool intel_bios_encoder_supports_dyn_port_over_tc(const struct intel_bios_encoder_data *devdata);
> >  bool intel_bios_encoder_supports_dsi(const struct intel_bios_encoder_data *devdata);
> >  bool intel_bios_encoder_supports_dp_dual_mode(const struct intel_bios_encoder_data *devdata);
> >  bool intel_bios_encoder_is_lspcon(const struct intel_bios_encoder_data *devdata);
> > diff --git a/drivers/gpu/drm/i915/display/intel_vbt_defs.h b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> > index 70e31520c560..57fda5824c9c 100644
> > --- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> > +++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> > @@ -554,7 +554,8 @@ struct child_device_config {
> >  	u8 dvo_function;
> >  	u8 dp_usb_type_c:1;					/* 195+ */
> >  	u8 tbt:1;						/* 209+ */
> > -	u8 flags2_reserved:2;					/* 195+ */
> > +	u8 dedicated_external:1;				/* 264+ */
> > +	u8 dyn_port_over_tc:1;					/* 264+ */
> >  	u8 dp_port_trace_length:4;				/* 209+ */
> >  	u8 dp_gpio_index;					/* 195+ */
> >  	u16 dp_gpio_pin_num;					/* 195+ */
> > 
> > -- 
> > 2.51.0
> >