how to validate the data of ckeditor in CI - php

Question

I need to validate the data of ckeditor. Is there any way to validate it in CodeIgniter? I have tried like this.
In View:
<div class="col-sm-12 col-md-10">
<textarea class="ckeditor" name="desc" id="editor" required><?php echo set_value('desc', ''); ?></textarea>
<span class="error"><?php echo form_error('desc'); ?></span>
</div>
In controller:
$this->form_validation->set_rules('desc', 'Desc', 'required');
if ($this->form_validation->run() == FALSE) {
$this->add_Coachs();
} else {
$rs = $this->functional->insertBlog();
if ($rs == true) {
$this->session->set_flashdata('blog', 'Your Blog Submitted Successfully.Thank You!');
redirect('Wall');
} else {
$this->session->set_flashdata('blog', 'Blog Not Submitted');
redirect('Wall');
}
}
But here it executes the false condition. Can anyone tell me where I'm going wrong? Is there any way to resolve this problem?
Edited :
In model :
public function insertBlog() {
$full_name = $this->session->userdata('first_name') . " " . $this->session->userdata('last_name');
$email = $this->session->userdata('email');
$data = array(
'user_id' => $this->input->post('user_id'),
'full_name' => $full_name,
'email' => $email,
'desc' => $this->input->post('desc'),
'create_date' => date('Y-m-d h:i:s', now()),
'modify_date' => date('Y:m:d h:i:s'),
'start_date' => date('Y:m:d h:i:s'),
'end_date' => date('Y:m:d h:i:s'),
'status' => "Deactive",
'userby' => $this->input->post('user_id')
);
$rs = $this->db->insert('ult_latest_blog', $data);
return $rs;
}