drm/amd/display: expose skip_detection_link_training to debugfs

[Why] within dc link detecion, dp link training will be
executed for external sst dp. for debug purpose, we may
need skip dp link training.

[How] expose dc debug option to skip_detection_link_training
to debugfs
Reviewed-by: Roman Li <Roman.Li@amd.com>
Acked-by: Pavle Kotarac <Pavle.Kotarac@amd.com>
Signed-off-by: hersen wu <hersenxs.wu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c

@@ -3491,6 +3491,40 @@ DEFINE_SHOW_ATTRIBUTE(mst_topo);
 DEFINE_DEBUGFS_ATTRIBUTE(visual_confirm_fops, visual_confirm_get,
 			 visual_confirm_set, "%llu\n");
 
+
+/*
+ * Sets the DC skip_detection_link_training debug option from the given string.
+ * Example usage: echo 1 > /sys/kernel/debug/dri/0/amdgpu_skip_detection_link_training
+ */
+static int skip_detection_link_training_set(void *data, u64 val)
+{
+	struct amdgpu_device *adev = data;
+
+	if (val == 0)
+		adev->dm.dc->debug.skip_detection_link_training = false;
+	else
+		adev->dm.dc->debug.skip_detection_link_training = true;
+
+	return 0;
+}
+
+/*
+ * Reads the DC skip_detection_link_training debug option value into the given buffer.
+ * Example usage: cat /sys/kernel/debug/dri/0/amdgpu_dm_skip_detection_link_training
+ */
+static int skip_detection_link_training_get(void *data, u64 *val)
+{
+	struct amdgpu_device *adev = data;
+
+	*val = adev->dm.dc->debug.skip_detection_link_training;
+
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(skip_detection_link_training_fops,
+			 skip_detection_link_training_get,
+			 skip_detection_link_training_set, "%llu\n");
+
 /*
  * Dumps the DCC_EN bit for each pipe.
  * Example usage: cat /sys/kernel/debug/dri/0/amdgpu_dm_dcc_en
@@ -3584,6 +3618,9 @@ void dtn_debugfs_init(struct amdgpu_device *adev)
 	debugfs_create_file_unsafe("amdgpu_dm_visual_confirm", 0644, root, adev,
 				   &visual_confirm_fops);
 
+	debugfs_create_file_unsafe("amdgpu_dm_skip_detection_link_training", 0644, root, adev,
+				   &skip_detection_link_training_fops);
+
 	debugfs_create_file_unsafe("amdgpu_dm_dmub_tracebuffer", 0644, root,
 				   adev, &dmub_tracebuffer_fops);