drm/i915: Force a TypeC PHY disconnect during suspend/shutdown

Disconnect TypeC PHYs during system suspend and shutdown, even with the
corresponding TypeC sink still plugged to its connector, since leaving
the PHY connected causes havoc at least during system resume in the
presence of an Nvidia card.

Note that this will only make a difference in the TypeC DP alternate
mode, since in Thunderbolt alternate mode the PHY is never owned by the
display engine and there is no notion of PHY ownership in legacy mode
(the display engine being the only possible owner in that mode and the
TypeC subsystem not having anything to do with the port in that case).

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3500
Reported-and-tested-by: Chris Chiu <chris.chiu@canonical.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210610174223.605904-1-imre.deak@intel.com

1 files changed, 27 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_tc.c b/drivers/gpu/drm/i915/display/intel_tc.c
index c23c210a55f5..3ffece568ed9 100644
--- a/drivers/gpu/drm/i915/display/intel_tc.c
+++ b/drivers/gpu/drm/i915/display/intel_tc.c
@@ -556,7 +556,7 @@ intel_tc_port_get_target_mode(struct intel_digital_port *dig_port)
 }
 
 static void intel_tc_port_reset_mode(struct intel_digital_port *dig_port,
-				     int required_lanes)
+				     int required_lanes, bool force_disconnect)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
 	enum tc_port_mode old_tc_mode = dig_port->tc_mode;
@@ -572,7 +572,8 @@ static void intel_tc_port_reset_mode(struct intel_digital_port *dig_port,
 	}
 
 	icl_tc_phy_disconnect(dig_port);
-	icl_tc_phy_connect(dig_port, required_lanes);
+	if (!force_disconnect)
+		icl_tc_phy_connect(dig_port, required_lanes);
 
 	drm_dbg_kms(&i915->drm, "Port %s: TC port mode reset (%s -> %s)\n",
 		    dig_port->tc_port_name,
@@ -662,7 +663,7 @@ bool intel_tc_port_connected(struct intel_encoder *encoder)
 }
 
 static void __intel_tc_port_lock(struct intel_digital_port *dig_port,
-				 int required_lanes)
+				 int required_lanes, bool force_disconnect)
 {
 	struct drm_i915_private *i915 = to_i915(dig_port->base.base.dev);
 	intel_wakeref_t wakeref;
@@ -676,8 +677,9 @@ static void __intel_tc_port_lock(struct intel_digital_port *dig_port,
 
 		tc_cold_wref = tc_cold_block(dig_port);
 
-		if (intel_tc_port_needs_reset(dig_port))
-			intel_tc_port_reset_mode(dig_port, required_lanes);
+		if (force_disconnect || intel_tc_port_needs_reset(dig_port))
+			intel_tc_port_reset_mode(dig_port, required_lanes,
+						 force_disconnect);
 
 		tc_cold_unblock(dig_port, tc_cold_wref);
 	}
@@ -688,7 +690,7 @@ static void __intel_tc_port_lock(struct intel_digital_port *dig_port,
 
 void intel_tc_port_lock(struct intel_digital_port *dig_port)
 {
-	__intel_tc_port_lock(dig_port, 1);
+	__intel_tc_port_lock(dig_port, 1, false);
 }
 
 void intel_tc_port_unlock(struct intel_digital_port *dig_port)
@@ -702,6 +704,24 @@ void intel_tc_port_unlock(struct intel_digital_port *dig_port)
 				      wakeref);
 }
 
+/**
+ * intel_tc_port_disconnect_phy: disconnect TypeC PHY from display port
+ * @dig_port: digital port
+ *
+ * Disconnect the given digital port from its TypeC PHY (handing back the
+ * control of the PHY to the TypeC subsystem). The only purpose of this
+ * function is to force the disconnect even with a TypeC display output still
+ * plugged to the TypeC connector, which is required by the TypeC firmwares
+ * during system suspend and shutdown. Otherwise - during the unplug event
+ * handling - the PHY ownership is released automatically by
+ * intel_tc_port_reset_mode(), when calling this function is not required.
+ */
+void intel_tc_port_disconnect_phy(struct intel_digital_port *dig_port)
+{
+	__intel_tc_port_lock(dig_port, 1, true);
+	intel_tc_port_unlock(dig_port);
+}
+
 bool intel_tc_port_ref_held(struct intel_digital_port *dig_port)
 {
 	return mutex_is_locked(&dig_port->tc_lock) ||
@@ -711,7 +731,7 @@ bool intel_tc_port_ref_held(struct intel_digital_port *dig_port)
 void intel_tc_port_get_link(struct intel_digital_port *dig_port,
 			    int required_lanes)
 {
-	__intel_tc_port_lock(dig_port, required_lanes);
+	__intel_tc_port_lock(dig_port, required_lanes, false);
 	dig_port->tc_link_refcount++;
 	intel_tc_port_unlock(dig_port);
 }