Re: [PATCH 27/32] drm/i915/vbt: Add fields dedicated_external and dyn_port_over_tc

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

On Wed, 15 Oct 2025, Gustavo Sousa <gustavo.sousa@intel.com> 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 make sure to update the accessor functions to take
> that into consideration.
>
> Bspec: 20124, 68954, 74304
> Cc: Shekhar Chauhan <shekhar.chauhan@intel.com>
> Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_bios.c     | 20 +++++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_bios.h     |  2 ++
>  drivers/gpu/drm/i915/display/intel_vbt_defs.h |  7 ++++++-
>  3 files changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
> index 3596dce84c28..e466728ced0f 100644
> --- a/drivers/gpu/drm/i915/display/intel_bios.c
> +++ b/drivers/gpu/drm/i915/display/intel_bios.c
> @@ -2777,7 +2777,7 @@ 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;
> @@ -3714,14 +3714,32 @@ int intel_bios_hdmi_ddc_pin(const struct intel_bios_encoder_data *devdata)
>  
>  bool intel_bios_encoder_supports_typec_usb(const struct intel_bios_encoder_data *devdata)
>  {
> +	if (intel_bios_encoder_is_dedicated_external(devdata))
> +		return false;
> +

We already have mechanisms for this. Please don't pollute the functions.

dp_usb_type_c should just be set to 0 in a new sanitize_something()
function at the end of parse_ddi_port()

>  	return devdata->display->vbt.version >= 195 && devdata->child.dp_usb_type_c;
>  }
>  
>  bool intel_bios_encoder_supports_tbt(const struct intel_bios_encoder_data *devdata)
>  {
> +	if (intel_bios_encoder_is_dedicated_external(devdata))
> +		return false;
> +

Ditto.

tbt should just be set to 0 in a new sanitize_something() function at
the end of parse_ddi_port()

>  	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..f07ab64a8d97 100644
> --- a/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> +++ b/drivers/gpu/drm/i915/display/intel_vbt_defs.h
> @@ -554,7 +554,12 @@ struct child_device_config {
>  	u8 dvo_function;
>  	u8 dp_usb_type_c:1;					/* 195+ */
>  	u8 tbt:1;						/* 209+ */
> -	u8 flags2_reserved:2;					/* 195+ */
> +	/*
> +	 * Fields dp_usb_type_c and tbt must be ignored when
> +	 * dedicated_external is set.
> +	 */

We can add that info in the sanitize function. We don't generally add a
whole lot of explanatory text here, because if we did, the file would be
10x consisting mostly of VBT quirk explanations.

> +	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+ */

-- 
Jani Nikula, Intel