drm/i915/dp_link_training: Introduce link training state struct

Start isolating the link training state from the generic DP code by
introducing a separate intel_dp_link_training state struct.

Allocate the state so it can remain opaque within its own module.

Follow-up changes will move link training fields from the DP struct to
the link training state.

v2: Remove unnecessary function documentation. (Jani)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260601093836.3057345-2-imre.deak@intel.com

drivers/gpu/drm/i915/display/g4x_dp.c

@@ -1252,10 +1252,13 @@ static void g4x_dp_suspend_complete(struct intel_encoder *encoder)
 
 static void intel_dp_encoder_destroy(struct drm_encoder *encoder)
 {
+	struct intel_digital_port *dig_port = enc_to_dig_port(to_intel_encoder(encoder));
+
 	intel_dp_encoder_flush_work(encoder);
 
 	drm_encoder_cleanup(encoder);
-	kfree(enc_to_dig_port(to_intel_encoder(encoder)));
+	intel_dp_link_cleanup(&dig_port->dp);
+	kfree(dig_port);
 }
 
 static void intel_dp_encoder_reset(struct drm_encoder *encoder)
@@ -1350,6 +1353,9 @@ bool g4x_dp_init(struct intel_display *display,
 	intel_encoder->audio_enable = g4x_dp_audio_enable;
 	intel_encoder->audio_disable = g4x_dp_audio_disable;
 
+	if (intel_dp_link_init(&dig_port->dp) != 0)
+		goto err_dp_init;
+
 	if ((display->platform.ivybridge && port == PORT_A) ||
 	    (HAS_PCH_CPT(display) && port != PORT_A)) {
 		dig_port->dp.set_link_train = cpt_set_link_train;
@@ -1419,6 +1425,8 @@ bool g4x_dp_init(struct intel_display *display,
 	return true;
 
 err_init_connector:
+	intel_dp_link_cleanup(&dig_port->dp);
+err_dp_init:
 	drm_encoder_cleanup(encoder);
 err_encoder_init:
 	kfree(intel_connector);

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

@@ -4654,6 +4654,7 @@ static void intel_ddi_encoder_destroy(struct drm_encoder *encoder)
 
 	drm_encoder_cleanup(encoder);
 	kfree(dig_port->hdcp.port_data.streams);
+	intel_dp_link_cleanup(&dig_port->dp);
 	kfree(dig_port);
 }
 
@@ -4691,11 +4692,16 @@ static int intel_ddi_init_dp_connector(struct intel_digital_port *dig_port)
 	struct intel_display *display = to_intel_display(dig_port);
 	struct intel_connector *connector;
 	enum port port = dig_port->base.port;
+	int err;
 
 	connector = intel_connector_alloc();
 	if (!connector)
 		return -ENOMEM;
 
+	err = intel_dp_link_init(&dig_port->dp);
+	if (err)
+		goto err_dp_init;
+
 	dig_port->dp.output_reg = DDI_BUF_CTL(port);
 	if (DISPLAY_VER(display) >= 14)
 		dig_port->dp.prepare_link_retrain = mtl_ddi_prepare_link_retrain;
@@ -4708,8 +4714,9 @@ static int intel_ddi_init_dp_connector(struct intel_digital_port *dig_port)
 	dig_port->dp.preemph_max = intel_ddi_dp_preemph_max;
 
 	if (!intel_dp_init_connector(dig_port, connector)) {
-		kfree(connector);
-		return -EINVAL;
+		err = -EINVAL;
+
+		goto err_init_connector;
 	}
 
 	if (dig_port->base.type == INTEL_OUTPUT_EDP) {
@@ -4725,6 +4732,13 @@ static int intel_ddi_init_dp_connector(struct intel_digital_port *dig_port)
 	}
 
 	return 0;
+
+err_init_connector:
+	intel_dp_link_cleanup(&dig_port->dp);
+err_dp_init:
+	kfree(connector);
+
+	return err;
 }
 
 static void intel_ddi_cleanup_dp_connector(struct intel_digital_port *dig_port)
@@ -4733,6 +4747,7 @@ static void intel_ddi_cleanup_dp_connector(struct intel_digital_port *dig_port)
 	struct intel_connector *connector = intel_dp->attached_connector;
 
 	intel_dp_cleanup_connector(dig_port, connector);
+	intel_dp_link_cleanup(intel_dp);
 	kfree(connector);
 }
 

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

@@ -58,6 +58,7 @@ struct cec_notifier;
 struct drm_printer;
 struct intel_connector;
 struct intel_ddi_buf_trans;
+struct intel_dp_link_training;
 struct intel_fbc;
 struct intel_global_objs_state;
 struct intel_hdcp_shim;
@@ -1858,6 +1859,7 @@ struct intel_dp {
 		int seq_train_failures;
 		int force_train_failure;
 		bool force_retrain;
+		struct intel_dp_link_training *training;
 	} link;
 	bool reset_link_params;
 	int mso_link_count;

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

@@ -7649,3 +7649,17 @@ u8 intel_dp_as_sdp_transmission_time(void)
 
 	return DP_PR_AS_SDP_SETUP_TIME_T1;
 }
+
+int intel_dp_link_init(struct intel_dp *intel_dp)
+{
+	intel_dp->link.training = intel_dp_link_training_init(intel_dp);
+	if (!intel_dp->link.training)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void intel_dp_link_cleanup(struct intel_dp *intel_dp)
+{
+	intel_dp_link_training_cleanup(intel_dp->link.training);
+}

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

@@ -243,4 +243,7 @@ bool intel_dp_joiner_candidate_valid(struct intel_connector *connector,
 
 u8 intel_dp_as_sdp_transmission_time(void);
 
+int intel_dp_link_init(struct intel_dp *intel_dp);
+void intel_dp_link_cleanup(struct intel_dp *intel_dp);
+
 #endif /* __INTEL_DP_H__ */

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

@@ -62,6 +62,10 @@
 
 #define MAX_SEQ_TRAIN_FAILURES 2
 
+struct intel_dp_link_training {
+	struct intel_dp *dp;
+};
+
 static void intel_dp_reset_lttpr_common_caps(struct intel_dp *intel_dp)
 {
 	memset(intel_dp->lttpr_common_caps, 0, sizeof(intel_dp->lttpr_common_caps));
@@ -2233,3 +2237,21 @@ void intel_dp_link_training_debugfs_add(struct intel_connector *connector)
 	debugfs_create_file("i915_dp_link_retrain_disabled", 0444, root,
 			    connector, &i915_dp_link_retrain_disabled_fops);
 }
+
+struct intel_dp_link_training *intel_dp_link_training_init(struct intel_dp *intel_dp)
+{
+	struct intel_dp_link_training *link_training;
+
+	link_training = kzalloc_obj(*link_training);
+	if (!link_training)
+		return NULL;
+
+	link_training->dp = intel_dp;
+
+	return link_training;
+}
+
+void intel_dp_link_training_cleanup(struct intel_dp_link_training *link_training)
+{
+	kfree(link_training);
+}

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

@@ -12,6 +12,7 @@ struct intel_atomic_state;
 struct intel_connector;
 struct intel_crtc_state;
 struct intel_dp;
+struct intel_dp_link_training;
 
 int intel_dp_read_dprx_caps(struct intel_dp *intel_dp, u8 dpcd[DP_RECEIVER_CAP_SIZE]);
 int intel_dp_init_lttpr_and_dprx_caps(struct intel_dp *intel_dp);
@@ -56,4 +57,7 @@ void intel_dp_128b132b_sdp_crc16(struct intel_dp *intel_dp,
 
 void intel_dp_link_training_debugfs_add(struct intel_connector *connector);
 
+struct intel_dp_link_training *intel_dp_link_training_init(struct intel_dp *intel_dp);
+void intel_dp_link_training_cleanup(struct intel_dp_link_training *link_training);
+
 #endif /* __INTEL_DP_LINK_TRAINING_H__ */