Re: [PATCH 2/5] drm/i915/tc: Add separate intel_tc_phy_port_to_tc() for TC DDI/PHY ports

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

On Thu, 20 Nov 2025, Imre Deak <imre.deak@intel.com> wrote:
> intel_port_to_tc() returns the PORT_TC1..6 -> TC_PORT_1..6 mapping only
> for DDI ports that are connected to a TypeC PHY. In some cases this
> mapping is also required for TypeC DDI ports which are not connected to
> a TypeC PHY. Such DDI ports are the PORT_TC1..4 ports on RKL/ADLS/BMG.
>
> Add a separate intel_tc_phy_to_tc() helper to return the mapping for
> ports connected to a TypeC PHY, and make all the current users - which
> expect this semantic - call this helper. A follow-up change will need to
> get the same mapping for TypeC DDI ports not connected to a TypeC PHY,
> leave intel_port_to_tc() exported for that.

The TC port and phy stuff in our driver never cease to confuse me. And I
know you've explained all this to me several times.

I think we need some "TC port and phy for dummies" (that's me)
documentation comment somewhere in intel_tc.c that we (I) can refer to.

I also feel like the whole mess of intel_ddi_encoder_name() underlines
how problematic the concepts are. Moreover, I think intel_bios.c logs
the ports incorrectly.


BR,
Jani.


> Cc: Suraj Kandpal <suraj.kandpal@intel.com>
> Cc: Mika Kahola <mika.kahola@intel.com>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c     |  4 ++--
>  drivers/gpu/drm/i915/display/intel_display.c | 23 ++++++++++++++++----
>  drivers/gpu/drm/i915/display/intel_display.h |  1 +
>  3 files changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index 8471bdab5c62f..ed9798b0ec009 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -5148,7 +5148,7 @@ static const char *intel_ddi_encoder_name(struct intel_display *display,
>  			       port_name(port - PORT_D_XELPD + PORT_D),
>  			       phy_name(phy));
>  	} else if (DISPLAY_VER(display) >= 12) {
> -		enum tc_port tc_port = intel_port_to_tc(display, port);
> +		enum tc_port tc_port = intel_tc_phy_port_to_tc(display, port);
>  
>  		seq_buf_printf(s, "DDI %s%c/PHY %s%c",
>  			       port >= PORT_TC1 ? "TC" : "",
> @@ -5156,7 +5156,7 @@ static const char *intel_ddi_encoder_name(struct intel_display *display,
>  			       tc_port != TC_PORT_NONE ? "TC" : "",
>  			       tc_port != TC_PORT_NONE ? tc_port_name(tc_port) : phy_name(phy));
>  	} else if (DISPLAY_VER(display) >= 11) {
> -		enum tc_port tc_port = intel_port_to_tc(display, port);
> +		enum tc_port tc_port = intel_tc_phy_port_to_tc(display, port);
>  
>  		seq_buf_printf(s, "DDI %c%s/PHY %s%c",
>  			       port_name(port),
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 6c8a7f63111ec..a8a3e80001870 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -1859,17 +1859,32 @@ enum phy intel_port_to_phy(struct intel_display *display, enum port port)
>  }
>  
>  /* Prefer intel_encoder_to_tc() */
> +/*
> + * Return TC_PORT_1..I915_MAX_TC_PORTS for any TypeC DDI port. The function
> + * can be also called for TypeC DDI ports not connected to a TypeC PHY such as
> + * the PORT_TC1..4 ports on RKL/ADLS/BMG.
> + */
>  enum tc_port intel_port_to_tc(struct intel_display *display, enum port port)
>  {
> -	if (!intel_phy_is_tc(display, intel_port_to_phy(display, port)))
> -		return TC_PORT_NONE;
> -
>  	if (DISPLAY_VER(display) >= 12)
>  		return TC_PORT_1 + port - PORT_TC1;
>  	else
>  		return TC_PORT_1 + port - PORT_C;
>  }
>  
> +/*
> + * Return TC_PORT_1..I915_MAX_TC_PORTS for TypeC DDI ports connected to a TypeC PHY.
> + * Note that on RKL, ADLS, BMG the PORT_TC1..4 ports are connected to a non-TypeC
> + * PHY, so on those platforms the function returns TC_PORT_NONE.
> + */
> +enum tc_port intel_tc_phy_port_to_tc(struct intel_display *display, enum port port)
> +{
> +	if (!intel_phy_is_tc(display, intel_port_to_phy(display, port)))
> +		return TC_PORT_NONE;
> +
> +	return intel_port_to_tc(display, port);
> +}
> +
>  enum phy intel_encoder_to_phy(struct intel_encoder *encoder)
>  {
>  	struct intel_display *display = to_intel_display(encoder);
> @@ -1902,7 +1917,7 @@ enum tc_port intel_encoder_to_tc(struct intel_encoder *encoder)
>  {
>  	struct intel_display *display = to_intel_display(encoder);
>  
> -	return intel_port_to_tc(display, encoder->port);
> +	return intel_tc_phy_port_to_tc(display, encoder->port);
>  }
>  
>  enum intel_display_power_domain
> diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> index bcc6ccb69d2b5..f8e6e4e827222 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.h
> +++ b/drivers/gpu/drm/i915/display/intel_display.h
> @@ -451,6 +451,7 @@ bool intel_phy_is_combo(struct intel_display *display, enum phy phy);
>  bool intel_phy_is_tc(struct intel_display *display, enum phy phy);
>  bool intel_phy_is_snps(struct intel_display *display, enum phy phy);
>  enum tc_port intel_port_to_tc(struct intel_display *display, enum port port);
> +enum tc_port intel_tc_phy_port_to_tc(struct intel_display *display, enum port port);
>  
>  enum phy intel_encoder_to_phy(struct intel_encoder *encoder);
>  bool intel_encoder_is_combo(struct intel_encoder *encoder);

-- 
Jani Nikula, Intel