drm/i915/mst: abstract intel_dp_mst_source_support()

Add a function for checking source MST support. Drop intel_dp->can_mst
and use intel_dp->mst_mgr.cbs to indicate the same. It's the single
point of truth without additional state variables. In code, "source
support" is also self-documenting as opposed to the vague "can mst".
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211006101618.22066-1-jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_display_debugfs.c

@@ -7,12 +7,13 @@
 #include <drm/drm_fourcc.h>
 
 #include "i915_debugfs.h"
+#include "intel_de.h"
 #include "intel_display_debugfs.h"
 #include "intel_display_power.h"
-#include "intel_de.h"
 #include "intel_display_types.h"
 #include "intel_dmc.h"
 #include "intel_dp.h"
+#include "intel_dp_mst.h"
 #include "intel_drrs.h"
 #include "intel_fbc.h"
 #include "intel_hdcp.h"
@@ -1379,7 +1380,7 @@ static int i915_dp_mst_info(struct seq_file *m, void *unused)
 			continue;
 
 		dig_port = enc_to_dig_port(intel_encoder);
-		if (!dig_port->dp.can_mst)
+		if (!intel_dp_mst_source_support(&dig_port->dp))
 			continue;
 
 		seq_printf(m, "MST Source Port [ENCODER:%d:%s]\n",

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -1574,7 +1574,6 @@ struct intel_dp {
 
 	struct intel_pps pps;
 
-	bool can_mst; /* this port supports mst */
 	bool is_mst;
 	int active_mst_links;
 

drivers/gpu/drm/i915/display/intel_dp.c

@@ -2667,7 +2667,7 @@ intel_dp_can_mst(struct intel_dp *intel_dp)
 	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
 
 	return i915->params.enable_dp_mst &&
-		intel_dp->can_mst &&
+		intel_dp_mst_source_support(intel_dp) &&
 		drm_dp_read_mst_cap(&intel_dp->aux, intel_dp->dpcd);
 }
 
@@ -2682,10 +2682,10 @@ intel_dp_configure_mst(struct intel_dp *intel_dp)
 	drm_dbg_kms(&i915->drm,
 		    "[ENCODER:%d:%s] MST support: port: %s, sink: %s, modparam: %s\n",
 		    encoder->base.base.id, encoder->base.name,
-		    yesno(intel_dp->can_mst), yesno(sink_can_mst),
+		    yesno(intel_dp_mst_source_support(intel_dp)), yesno(sink_can_mst),
 		    yesno(i915->params.enable_dp_mst));
 
-	if (!intel_dp->can_mst)
+	if (!intel_dp_mst_source_support(intel_dp))
 		return;
 
 	intel_dp->is_mst = sink_can_mst &&
@@ -5085,7 +5085,7 @@ void intel_dp_mst_suspend(struct drm_i915_private *dev_priv)
 
 		intel_dp = enc_to_intel_dp(encoder);
 
-		if (!intel_dp->can_mst)
+		if (!intel_dp_mst_source_support(intel_dp))
 			continue;
 
 		if (intel_dp->is_mst)
@@ -5109,7 +5109,7 @@ void intel_dp_mst_resume(struct drm_i915_private *dev_priv)
 
 		intel_dp = enc_to_intel_dp(encoder);
 
-		if (!intel_dp->can_mst)
+		if (!intel_dp_mst_source_support(intel_dp))
 			continue;
 
 		ret = drm_dp_mst_topology_mgr_resume(&intel_dp->mst_mgr,

drivers/gpu/drm/i915/display/intel_dp_mst.c

@@ -977,24 +977,31 @@ intel_dp_mst_encoder_init(struct intel_digital_port *dig_port, int conn_base_id)
 					   dig_port->max_lanes,
 					   max_source_rate,
 					   conn_base_id);
-	if (ret)
+	if (ret) {
+		intel_dp->mst_mgr.cbs = NULL;
 		return ret;
-
-	intel_dp->can_mst = true;
+	}
 
 	return 0;
 }
 
+bool intel_dp_mst_source_support(struct intel_dp *intel_dp)
+{
+	return intel_dp->mst_mgr.cbs;
+}
+
 void
 intel_dp_mst_encoder_cleanup(struct intel_digital_port *dig_port)
 {
 	struct intel_dp *intel_dp = &dig_port->dp;
 
-	if (!intel_dp->can_mst)
+	if (!intel_dp_mst_source_support(intel_dp))
 		return;
 
 	drm_dp_mst_topology_mgr_destroy(&intel_dp->mst_mgr);
 	/* encoders will get killed by normal cleanup */
+
+	intel_dp->mst_mgr.cbs = NULL;
 }
 
 bool intel_dp_mst_is_master_trans(const struct intel_crtc_state *crtc_state)

drivers/gpu/drm/i915/display/intel_dp_mst.h

@@ -8,13 +8,15 @@
 
 #include <linux/types.h>
 
-struct intel_digital_port;
 struct intel_crtc_state;
+struct intel_digital_port;
+struct intel_dp;
 
 int intel_dp_mst_encoder_init(struct intel_digital_port *dig_port, int conn_id);
 void intel_dp_mst_encoder_cleanup(struct intel_digital_port *dig_port);
 int intel_dp_mst_encoder_active_links(struct intel_digital_port *dig_port);
 bool intel_dp_mst_is_master_trans(const struct intel_crtc_state *crtc_state);
 bool intel_dp_mst_is_slave_trans(const struct intel_crtc_state *crtc_state);
+bool intel_dp_mst_source_support(struct intel_dp *intel_dp);
 
 #endif /* __INTEL_DP_MST_H__ */