Re: [PATCH v4 04/11] drm/i915/display: Handle dedicated external ports in intel_encoder_is_tc()

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

On Fri, Nov 07, 2025 at 09:05:37PM -0300, Gustavo Sousa wrote:
> Starting with Xe3p_LPD, the VBT has a new field, called in the driver
> "dedicated_external", which tells that a Type-C capable port is
> physically connected to a PHY outside of the Type-C subsystem.  When
> that's the case, the driver must not do the extra Type-C programming for
> that port.  Update intel_encoder_is_tc() to check for that case.
> 
> While at it, add a note to intel_phy_is_tc() to remind us that it is
> about whether the respective port is a Type-C capable port rather than
> the PHY itself.
> 
> (Maybe it would be a nice idea to rename intel_phy_is_tc()?)
> 
> Note that this was handled with a new bool member added to struct
> intel_digital_port instead of having querying the VBT directly because
> VBT memory is freed (intel_bios_driver_remove) before encoder cleanup
> (intel_ddi_encoder_destroy), which would cause an oops to happen when
> the latter calls intel_encoder_is_tc().  This could be fixed by keeping
> VBT data around longer, but that's left for a follow-up work, if deemed
> necessary.
> 
> v2:
>   - Drop printing info about dedicated external, now that we are doing
>     it when parsing the VBT. (Jani)
>   - Add a FIXME comment on the code explaining why we need to store
>     dedicated_external in struct intel_digital_port. (Jani)
> 
> 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_ddi.c           | 11 +++++++++++
>  drivers/gpu/drm/i915/display/intel_display.c       | 19 ++++++++++++++++++-
>  drivers/gpu/drm/i915/display/intel_display_types.h |  1 +
>  3 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 733ef4559131..d9aaeafd1570 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -5376,6 +5376,17 @@ void intel_ddi_init(struct intel_display *display,
>  			goto err;
>  	}
>  
> +	/*
> +	 * FIXME: We currently need to store dedicated_external because devdata
> +	 * does not live long enough for when intel_encoder_is_tc() is called on
> +	 * the unbind path.  This needs to be fixed by making sure that the VBT
> +	 * data is kept long enough, so that
> +	 * intel_bios_encoder_is_dedicated_external() can be called directly
> +	 * from intel_encoder_is_tc().
> +	 */
> +	if (intel_bios_encoder_is_dedicated_external(devdata))
> +		dig_port->dedicated_external = true;
> +
>  	if (intel_encoder_is_tc(encoder)) {
>  		bool is_legacy =
>  			!intel_bios_encoder_supports_typec_usb(devdata) &&
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 25986bd8fbdd..431f7f030a9b 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -1800,7 +1800,17 @@ bool intel_phy_is_combo(struct intel_display *display, enum phy phy)
>  		return false;
>  }
>  
> -/* Prefer intel_encoder_is_tc() */
> +/*
> + * This function returns true if the DDI port respective to the PHY enumeration
> + * is a Type-C capable port.
> + *
> + * Depending on the VBT, the port might be configured
> + * as a "dedicated external" port, meaning that actual physical PHY is outside
> + * of the Type-C subsystem and, as such, not really a "Type-C PHY".
> + *
> + * Prefer intel_encoder_is_tc(), especially if you really need to know if we
> + * are dealing with Type-C connections.
> + */
>  bool intel_phy_is_tc(struct intel_display *display, enum phy phy)
>  {
>  	/*
> @@ -1885,6 +1895,13 @@ bool intel_encoder_is_tc(struct intel_encoder *encoder)
>  {
>  	struct intel_display *display = to_intel_display(encoder);
>  
> +	if (intel_encoder_is_dig_port(encoder)) {
> +		struct intel_digital_port *dig_port = enc_to_dig_port(encoder);

Just dig_port = enc_to_dig_port(encoder); ... if (dig_port &&
dig_port->dedicated_external) would be simpler and would be also more
consistent wrt. MST encoders.

> +
> +		if (dig_port->dedicated_external)
> +			return false;
> +	}
> +
>  	return intel_phy_is_tc(display, intel_encoder_to_phy(encoder));
>  }
>  
> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
> index 00600134bda0..8bf392bc0d5d 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
> @@ -1937,6 +1937,7 @@ struct intel_digital_port {
>  	bool lane_reversal;
>  	bool ddi_a_4_lanes;
>  	bool release_cl2_override;
> +	bool dedicated_external;
>  	u8 max_lanes;
>  	/* Used for DP and ICL+ TypeC/DP and TypeC/HDMI ports. */
>  	enum aux_ch aux_ch;
> 
> -- 
> 2.51.0
>