[Intel-gfx] [PATCH v2] drm/i915/icl: Add TypeC ports only if VBT is present

[Imre Deak]

We can't safely probe Type C ports, whether they are a legacy or a
USB/Thunderbolt DP Alternate Type C port. This would require performing
the TypeC connect sequence - as described by the specification - but
that may have unwanted side-effects. These side-effects include at least
- without completeness - timeouts during AUX power well enabling and
subsequent PLL enabling errors.

To safely identify these ports we really need VBT, which has the proper
flag for this (ddi_vbt_port_info::supports_typec_usb, supports_tbt).
Based on the above disable Type C ports if we can't load VBT for some
reason.

v2:
- Notice that we disable TypeC ports completely and simplify accordingly
  (Jose).
- Add code comment explaining why we disabled the ports. (Jani)

Cc: Jani Nikula <jani.nikula at intel.com>
Cc: Paulo Zanoni <paulo.r.zanoni at intel.com>
Cc: Jose Roberto de Souza <jose.souza at intel.com>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 drivers/gpu/drm/i915/intel_bios.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
index 561a4f9f044c..b508d8a735e0 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -1663,6 +1663,13 @@ init_vbt_missing_defaults(struct drm_i915_private *dev_priv)
 		struct ddi_vbt_port_info *info =
 			&dev_priv->vbt.ddi_port_info[port];
 
+		/*
+		 * VBT has the TypeC mode (native,TBT/USB) and we don't want
+		 * to detect it.
+		 */
+		if (intel_port_is_tc(dev_priv, port))
+			continue;
+
 		info->supports_dvi = (port != PORT_A && port != PORT_E);
 		info->supports_hdmi = info->supports_dvi;
 		info->supports_dp = (port != PORT_E);
-- 
2.13.2