drm/i915: Add state verification for the TypeC port mode

Add state verification for the TypeC port mode wrt. the port's AUX power
well enabling/disabling. Also check the correctness of changing the port
mode:
- When enabling/disabling the AUX power well for a TypeC port we must hold
  the TypeC port lock - the case for AUX transfers - or hold a Type C
  port link reference - the case for modeset enabling/disabling.
- When changing the TypeC port mode the port's AUX power domain must be
  disabled.

v2: (Ville)
- Simplify power_well_async_ref_count().
- Fix the commit log, clarifying what are the valid conditions to
  enable/disable the AUX power wells.

Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190628143635.22066-22-imre.deak@intel.com

1 files changed, 8 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_tc.h b/drivers/gpu/drm/i915/display/intel_tc.h
index 31af7be96070..8adc107cdbcb 100644
--- a/drivers/gpu/drm/i915/display/intel_tc.h
+++ b/drivers/gpu/drm/i915/display/intel_tc.h
@@ -7,8 +7,8 @@
 #define __INTEL_TC_H__
 
 #include <linux/types.h>
-
-struct intel_digital_port;
+#include <linux/mutex.h>
+#include "intel_drv.h"
 
 void icl_tc_phy_disconnect(struct intel_digital_port *dig_port);
 
@@ -23,6 +23,12 @@ void intel_tc_port_get_link(struct intel_digital_port *dig_port,
 			    int required_lanes);
 void intel_tc_port_put_link(struct intel_digital_port *dig_port);
 
+static inline int intel_tc_port_ref_held(struct intel_digital_port *dig_port)
+{
+	return mutex_is_locked(&dig_port->tc_lock) ||
+	       dig_port->tc_link_refcount;
+}
+
 void intel_tc_port_init(struct intel_digital_port *dig_port, bool is_legacy);
 
 #endif /* __INTEL_TC_H__ */