[PATCH v3 24/29] drm/i915/display: Handle dedicated external ports in intel_encoder_is_tc()

[Gustavo Sousa <gustavo.sousa@intel.com>]

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);
+
+		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