file foto tidak ada setelah di inputkan

//views
<div class="form-group">
                        <label class="control-label col-md-3 col-sm-3 col-xs-12" for="char">Foto <?php echo form_error('foto'); echo $this->session->flashdata('foto');?> </label>
                        <div class="col-md-6 col-sm-6 col-xs-12">
                            <input type="file" name="foto" id="foto" required onchange="previewImage();" value="<?php echo $foto;?>">

                            <img id="image-preview" alt="image preview"/>
                        </div>
                    </div>
                    <style type="text/css">
                        #image-preview{
                            display:none;
                            width : 100px;
                            height:120px;
                        }
                    </style>
                    <script>
                        function previewImage() {
                            document.getElementById("image-preview").style.display = "block";
                            var oFReader = new FileReader();
                             oFReader.readAsDataURL(document.getElementById("foto").files[0]);

                            oFReader.onload = function(oFREvent) {
                              document.getElementById("image-preview").src = oFREvent.target.result;
                            };
                        };
                    </script>

//controllel
public function create_action_mhs()
    {
        $config['upload_path']          = './gambar/';
        $config['allowed_types']        = 'gif|jpg|png';
        $config['max_size']             = 10;
        //$config['max_width']            = 1024;
        //$config['max_height']           = 768;

        $this->load->library('upload', $config);

        $this->rules_mhs();

        if ($this->form_validation->run() == FALSE) {
            $this->create_mhs();
        }
        elseif(! $this->upload->do_upload($this->input->post('foto',TRUE))){
            $error9 = array('foto' => $this->upload->display_errors());
            $this->session->set_flashdata($error9);
            //redirect(site_url('super_admin/create_mhs'));

             $this->create_mhs();
        }
        else {
            date_default_timezone_set('Asia/jakarta');
            $user=$this->ion_auth->user()->row();
            if(empty($this->input->post('tgl_lahir',TRUE)))
                $tgl="";
            else
                $tgl=date('Y-m-d', strtotime($this->input->post('tgl_lahir',TRUE)));

             $this->upload->data();

            $data = array(
                'nama'            => $this->input->post('nama',TRUE),
                'npm'             => $this->input->post('npm',TRUE),
                'fakultas'        => $this->input->post('fakultas',TRUE),
                'jurusan'         => $this->input->post('jurusan',TRUE),
                'semester'        => $this->input->post('semester',TRUE),
                //'kamar'           => $this->input->post('kamar',TRUE),
                //'operator' => $this->input->post('operator',TRUE),
                'operator'        => $user->first_name.' '.$user->last_name,
                'noHP'            => $this->input->post('noHP',TRUE),
                'j_k'             => $this->input->post('j_k',TRUE),
                'ttl'             => $this->input->post('ttl',TRUE),
                'sertifikat_ldik' => $this->input->post('sertifikat_ldik',TRUE),
                'foto'            => $this->input->post('foto',TRUE),
                'bahasa'          => implode(" ",$this->input->post('bahasa',TRUE)),
                'hobi'            => $this->input->post('hobi',TRUE),
                'keahlian'        => $this->input->post('keahlian',TRUE),
                'cita_cita'       => $this->input->post('cita_cita',TRUE),
                'tgl_lahir'       => $tgl,
            );
            $this->admin_model->insert($data);
            //kamar_mhs
            /*$ambil_id_mhs   = $this->db->get_where('daftar_mhs',array('npm'=>$this->input->post('npm',TRUE)));
            $ambil_id_kamar = $this->db->get_where('kamar',array('kamar'=>$this->input->post('kamar',TRUE)));
            foreach ($ambil_id_mhs->result() as $main){
                foreach ($ambil_id_kamar->result() as $mhs){
                    $kamar_id=$mhs->id;
                    $mhs_id=$main->id;

                }
            }

            $data_kamar=array(
                'id_mhs'   => $mhs_id,
                'id_kamar' => $kamar_id
            );
             $this->mhs_kamar_model->insert($data_kamar);
            */
             //Data orang tua
             $ambil_id_mhs   = $this->db->get_where('daftar_mhs',array('npm'=>$this->input->post('npm',TRUE)));
            foreach ($ambil_id_mhs->result() as $mhs1){
                    $mhs_id=$mhs1->id;
            }
             $data_orang_tua = array(
        'nama_Ayah' => $this->input->post('nama_Ayah',TRUE),
        'noHP_Ayah' => $this->input->post('noHP_Ayah',TRUE),
        'nama_Ibu' => $this->input->post('nama_Ibu',TRUE),
        'noHP_Ibu' => $this->input->post('noHP_Ibu',TRUE),
        'provinsi' => $this->input->post('provinsi',TRUE),
        'kab' => $this->input->post('kab',TRUE),
        'kec' => $this->input->post('kec',TRUE),
        'desa' => $this->input->post('desa',TRUE),
        'rt' => $this->input->post('rt',TRUE),
        'id_mhs' => $mhs_id
        );

            $this->Data_orang_tua_model->insert($data_orang_tua);
            //END data orang tua

            $this->session->set_flashdata('message', 'Create Record Success');
            redirect(site_url('super_admin/mhs_list_ikhwan'));
        }
    }