Re: [Intel-gfx] [PATCH 11/14] drm/i915/tc: Assume a TC port is legacy if VBT says the port has HDMI

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Mar 16, 2023 at 03:17:21PM +0200, Imre Deak wrote:
> Since an HDMI output can only be enabled in legacy mode on TC ports,
> assume that VBT is wrong and the port is legacy if VBT says the port is
> non-legacy and has HDMI.
> 
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_ddi.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
> index c531fee888a49..e79da640759c3 100644
> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
> @@ -4494,6 +4494,13 @@ void intel_ddi_init(struct drm_i915_private *dev_priv, enum port port)
>  			!intel_bios_encoder_supports_typec_usb(devdata) &&
>  			!intel_bios_encoder_supports_tbt(devdata);
>  
> +		if (!is_legacy && init_hdmi) {
> +			drm_dbg_kms(&dev_priv->drm,
> +				    "VBT says port %c is non-legacy TC and has HDMI, assume it's legacy TC\n",
> +				    port_name(port));
> +			is_legacy = true;
> +		}

Have we actually seen this in practice? And does the port then actually
work correctly?

If not then I think I'd just WARN an bail here.

> +
>  		intel_tc_port_init(dig_port, is_legacy);
>  
>  		encoder->update_prepare = intel_ddi_update_prepare;
> -- 
> 2.37.1

-- 
Ville Syrjälä
Intel