SAFE public projects git trees. - safe/jmp/linux-2.6/blob - drivers/ide/ide-atapi.c

   1 /*
   2  * ATAPI support.
   3  */
   4
   5 #include <linux/kernel.h>
   6 #include <linux/cdrom.h>
   7 #include <linux/delay.h>
   8 #include <linux/ide.h>
   9 #include <scsi/scsi.h>
  10
  11 #ifdef DEBUG
  12 #define debug_log(fmt, args...) \
  13         printk(KERN_INFO "ide: " fmt, ## args)
  14 #else
  15 #define debug_log(fmt, args...) do {} while (0)
  16 #endif
  17
  18 static inline int dev_is_idecd(ide_drive_t *drive)
  19 {
  20         return (drive->media == ide_cdrom || drive->media == ide_optical) &&
  21                 !(drive->dev_flags & IDE_DFLAG_SCSI);
  22 }
  23
  24 /*
  25  * Check whether we can support a device,
  26  * based on the ATAPI IDENTIFY command results.
  27  */
  28 int ide_check_atapi_device(ide_drive_t *drive, const char *s)
  29 {
  30         u16 *id = drive->id;
  31         u8 gcw[2], protocol, device_type, removable, drq_type, packet_size;
  32
  33         *((u16 *)&gcw) = id[ATA_ID_CONFIG];
  34
  35         protocol    = (gcw[1] & 0xC0) >> 6;
  36         device_type =  gcw[1] & 0x1F;
  37         removable   = (gcw[0] & 0x80) >> 7;
  38         drq_type    = (gcw[0] & 0x60) >> 5;
  39         packet_size =  gcw[0] & 0x03;
  40
  41 #ifdef CONFIG_PPC
  42         /* kludge for Apple PowerBook internal zip */
  43         if (drive->media == ide_floppy && device_type == 5 &&
  44             !strstr((char *)&id[ATA_ID_PROD], "CD-ROM") &&
  45             strstr((char *)&id[ATA_ID_PROD], "ZIP"))
  46                 device_type = 0;
  47 #endif
  48
  49         if (protocol != 2)
  50                 printk(KERN_ERR "%s: %s: protocol (0x%02x) is not ATAPI\n",
  51                         s, drive->name, protocol);
  52         else if ((drive->media == ide_floppy && device_type != 0) ||
  53                  (drive->media == ide_tape && device_type != 1))
  54                 printk(KERN_ERR "%s: %s: invalid device type (0x%02x)\n",
  55                         s, drive->name, device_type);
  56         else if (removable == 0)
  57                 printk(KERN_ERR "%s: %s: the removable flag is not set\n",
  58                         s, drive->name);
  59         else if (drive->media == ide_floppy && drq_type == 3)
  60                 printk(KERN_ERR "%s: %s: sorry, DRQ type (0x%02x) not "
  61                         "supported\n", s, drive->name, drq_type);
  62         else if (packet_size != 0)
  63                 printk(KERN_ERR "%s: %s: packet size (0x%02x) is not 12 "
  64                         "bytes\n", s, drive->name, packet_size);
  65         else
  66                 return 1;
  67         return 0;
  68 }
  69 EXPORT_SYMBOL_GPL(ide_check_atapi_device);
  70
  71 /* PIO data transfer routine using the scatter gather table. */
  72 int ide_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
  73                     unsigned int bcount, int write)
  74 {
  75         ide_hwif_t *hwif = drive->hwif;
  76         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
  77         xfer_func_t *xf = write ? tp_ops->output_data : tp_ops->input_data;
  78         struct scatterlist *sg = pc->sg;
  79         char *buf;
  80         int count, done = 0;
  81
  82         while (bcount) {
  83                 count = min(sg->length - pc->b_count, bcount);
  84
  85                 if (PageHighMem(sg_page(sg))) {
  86                         unsigned long flags;
  87
  88                         local_irq_save(flags);
  89                         buf = kmap_atomic(sg_page(sg), KM_IRQ0) + sg->offset;
  90                         xf(drive, NULL, buf + pc->b_count, count);
  91                         kunmap_atomic(buf - sg->offset, KM_IRQ0);
  92                         local_irq_restore(flags);
  93                 } else {
  94                         buf = sg_virt(sg);
  95                         xf(drive, NULL, buf + pc->b_count, count);
  96                 }
  97
  98                 bcount -= count;
  99                 pc->b_count += count;
 100                 done += count;
 101
 102                 if (pc->b_count == sg->length) {
 103                         if (!--pc->sg_cnt)
 104                                 break;
 105                         pc->sg = sg = sg_next(sg);
 106                         pc->b_count = 0;
 107                 }
 108         }
 109
 110         if (bcount) {
 111                 printk(KERN_ERR "%s: %d leftover bytes, %s\n", drive->name,
 112                         bcount, write ? "padding with zeros"
 113                                       : "discarding data");
 114                 ide_pad_transfer(drive, write, bcount);
 115         }
 116
 117         return done;
 118 }
 119 EXPORT_SYMBOL_GPL(ide_io_buffers);
 120
 121 void ide_init_pc(struct ide_atapi_pc *pc)
 122 {
 123         memset(pc, 0, sizeof(*pc));
 124         pc->buf = pc->pc_buf;
 125         pc->buf_size = IDE_PC_BUFFER_SIZE;
 126 }
 127 EXPORT_SYMBOL_GPL(ide_init_pc);
 128
 129 /*
 130  * Generate a new packet command request in front of the request queue, before
 131  * the current request, so that it will be processed immediately, on the next
 132  * pass through the driver.
 133  */
 134 static void ide_queue_pc_head(ide_drive_t *drive, struct gendisk *disk,
 135                               struct ide_atapi_pc *pc, struct request *rq)
 136 {
 137         blk_rq_init(NULL, rq);
 138         rq->cmd_type = REQ_TYPE_SPECIAL;
 139         rq->cmd_flags |= REQ_PREEMPT;
 140         rq->buffer = (char *)pc;
 141         rq->rq_disk = disk;
 142         memcpy(rq->cmd, pc->c, 12);
 143         if (drive->media == ide_tape)
 144                 rq->cmd[13] = REQ_IDETAPE_PC1;
 145         ide_do_drive_cmd(drive, rq);
 146 }
 147
 148 /*
 149  * Add a special packet command request to the tail of the request queue,
 150  * and wait for it to be serviced.
 151  */
 152 int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,
 153                       struct ide_atapi_pc *pc)
 154 {
 155         struct request *rq;
 156         int error;
 157
 158         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
 159         rq->cmd_type = REQ_TYPE_SPECIAL;
 160         rq->buffer = (char *)pc;
 161         memcpy(rq->cmd, pc->c, 12);
 162         if (drive->media == ide_tape)
 163                 rq->cmd[13] = REQ_IDETAPE_PC1;
 164         error = blk_execute_rq(drive->queue, disk, rq, 0);
 165         blk_put_request(rq);
 166
 167         return error;
 168 }
 169 EXPORT_SYMBOL_GPL(ide_queue_pc_tail);
 170
 171 int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
 172 {
 173         struct ide_atapi_pc pc;
 174
 175         ide_init_pc(&pc);
 176         pc.c[0] = TEST_UNIT_READY;
 177
 178         return ide_queue_pc_tail(drive, disk, &pc);
 179 }
 180 EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);
 181
 182 int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
 183 {
 184         struct ide_atapi_pc pc;
 185
 186         ide_init_pc(&pc);
 187         pc.c[0] = START_STOP;
 188         pc.c[4] = start;
 189
 190         if (drive->media == ide_tape)
 191                 pc.flags |= PC_FLAG_WAIT_FOR_DSC;
 192
 193         return ide_queue_pc_tail(drive, disk, &pc);
 194 }
 195 EXPORT_SYMBOL_GPL(ide_do_start_stop);
 196
 197 int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
 198 {
 199         struct ide_atapi_pc pc;
 200
 201         if ((drive->dev_flags & IDE_DFLAG_DOORLOCKING) == 0)
 202                 return 0;
 203
 204         ide_init_pc(&pc);
 205         pc.c[0] = ALLOW_MEDIUM_REMOVAL;
 206         pc.c[4] = on;
 207
 208         return ide_queue_pc_tail(drive, disk, &pc);
 209 }
 210 EXPORT_SYMBOL_GPL(ide_set_media_lock);
 211
 212 void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
 213 {
 214         ide_init_pc(pc);
 215         pc->c[0] = REQUEST_SENSE;
 216         if (drive->media == ide_floppy) {
 217                 pc->c[4] = 255;
 218                 pc->req_xfer = 18;
 219         } else {
 220                 pc->c[4] = 20;
 221                 pc->req_xfer = 20;
 222         }
 223 }
 224 EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);
 225
 226 /*
 227  * Called when an error was detected during the last packet command.
 228  * We queue a request sense packet command in the head of the request list.
 229  */
 230 void ide_retry_pc(ide_drive_t *drive, struct gendisk *disk)
 231 {
 232         struct request *rq = &drive->request_sense_rq;
 233         struct ide_atapi_pc *pc = &drive->request_sense_pc;
 234
 235         (void)ide_read_error(drive);
 236         ide_create_request_sense_cmd(drive, pc);
 237         if (drive->media == ide_tape)
 238                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
 239         ide_queue_pc_head(drive, disk, pc, rq);
 240 }
 241 EXPORT_SYMBOL_GPL(ide_retry_pc);
 242
 243 int ide_scsi_expiry(ide_drive_t *drive)
 244 {
 245         struct ide_atapi_pc *pc = drive->pc;
 246
 247         debug_log("%s called for %lu at %lu\n", __func__,
 248                   pc->scsi_cmd->serial_number, jiffies);
 249
 250         pc->flags |= PC_FLAG_TIMEDOUT;
 251
 252         return 0; /* we do not want the IDE subsystem to retry */
 253 }
 254 EXPORT_SYMBOL_GPL(ide_scsi_expiry);
 255
 256 int ide_cd_expiry(ide_drive_t *drive)
 257 {
 258         struct request *rq = HWGROUP(drive)->rq;
 259         unsigned long wait = 0;
 260
 261         debug_log("%s: rq->cmd[0]: 0x%x\n", __func__, rq->cmd[0]);
 262
 263         /*
 264          * Some commands are *slow* and normally take a long time to complete.
 265          * Usually we can use the ATAPI "disconnect" to bypass this, but not all
 266          * commands/drives support that. Let ide_timer_expiry keep polling us
 267          * for these.
 268          */
 269         switch (rq->cmd[0]) {
 270         case GPCMD_BLANK:
 271         case GPCMD_FORMAT_UNIT:
 272         case GPCMD_RESERVE_RZONE_TRACK:
 273         case GPCMD_CLOSE_TRACK:
 274         case GPCMD_FLUSH_CACHE:
 275                 wait = ATAPI_WAIT_PC;
 276                 break;
 277         default:
 278                 if (!(rq->cmd_flags & REQ_QUIET))
 279                         printk(KERN_INFO "cmd 0x%x timed out\n",
 280                                          rq->cmd[0]);
 281                 wait = 0;
 282                 break;
 283         }
 284         return wait;
 285 }
 286 EXPORT_SYMBOL_GPL(ide_cd_expiry);
 287
 288 int ide_cd_get_xferlen(struct request *rq)
 289 {
 290         if (blk_fs_request(rq))
 291                 return 32768;
 292         else if (blk_sense_request(rq) || blk_pc_request(rq) ||
 293                          rq->cmd_type == REQ_TYPE_ATA_PC)
 294                 return rq->data_len;
 295         else
 296                 return 0;
 297 }
 298 EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);
 299
 300 /*
 301  * This is the usual interrupt handler which will be called during a packet
 302  * command.  We will transfer some of the data (as requested by the drive)
 303  * and will re-point interrupt handler to us.
 304  */
 305 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
 306 {
 307         struct ide_atapi_pc *pc = drive->pc;
 308         ide_hwif_t *hwif = drive->hwif;
 309         struct request *rq = hwif->hwgroup->rq;
 310         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 311         xfer_func_t *xferfunc;
 312         ide_expiry_t *expiry;
 313         unsigned int timeout, temp;
 314         u16 bcount;
 315         u8 stat, ireason, scsi = !!(drive->dev_flags & IDE_DFLAG_SCSI), dsc = 0;
 316
 317         debug_log("Enter %s - interrupt handler\n", __func__);
 318
 319         if (scsi) {
 320                 timeout = ide_scsi_get_timeout(pc);
 321                 expiry = ide_scsi_expiry;
 322         } else {
 323                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 324                                                        : WAIT_TAPE_CMD;
 325                 expiry = NULL;
 326         }
 327
 328         if (pc->flags & PC_FLAG_TIMEDOUT) {
 329                 drive->pc_callback(drive, 0);
 330                 return ide_stopped;
 331         }
 332
 333         /* Clear the interrupt */
 334         stat = tp_ops->read_status(hwif);
 335
 336         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 337                 if (hwif->dma_ops->dma_end(drive) ||
 338                     (drive->media == ide_tape && !scsi && (stat & ATA_ERR))) {
 339                         if (drive->media == ide_floppy && !scsi)
 340                                 printk(KERN_ERR "%s: DMA %s error\n",
 341                                         drive->name, rq_data_dir(pc->rq)
 342                                                      ? "write" : "read");
 343                         pc->flags |= PC_FLAG_DMA_ERROR;
 344                 } else {
 345                         pc->xferred = pc->req_xfer;
 346                         if (drive->pc_update_buffers)
 347                                 drive->pc_update_buffers(drive, pc);
 348                 }
 349                 debug_log("%s: DMA finished\n", drive->name);
 350         }
 351
 352         /* No more interrupts */
 353         if ((stat & ATA_DRQ) == 0) {
 354                 debug_log("Packet command completed, %d bytes transferred\n",
 355                           pc->xferred);
 356
 357                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 358
 359                 local_irq_enable_in_hardirq();
 360
 361                 if (drive->media == ide_tape && !scsi &&
 362                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
 363                         stat &= ~ATA_ERR;
 364
 365                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
 366                         /* Error detected */
 367                         debug_log("%s: I/O error\n", drive->name);
 368
 369                         if (drive->media != ide_tape || scsi) {
 370                                 pc->rq->errors++;
 371                                 if (scsi)
 372                                         goto cmd_finished;
 373                         }
 374
 375                         if (rq->cmd[0] == REQUEST_SENSE) {
 376                                 printk(KERN_ERR "%s: I/O error in request sense"
 377                                                 " command\n", drive->name);
 378                                 return ide_do_reset(drive);
 379                         }
 380
 381                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
 382
 383                         /* Retry operation */
 384                         ide_retry_pc(drive, rq->rq_disk);
 385
 386                         /* queued, but not started */
 387                         return ide_stopped;
 388                 }
 389 cmd_finished:
 390                 pc->error = 0;
 391
 392                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
 393                         dsc = 1;
 394
 395                 /* Command finished - Call the callback function */
 396                 drive->pc_callback(drive, dsc);
 397
 398                 return ide_stopped;
 399         }
 400
 401         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 402                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 403                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
 404                                 "in DMA mode\n", drive->name);
 405                 ide_dma_off(drive);
 406                 return ide_do_reset(drive);
 407         }
 408
 409         /* Get the number of bytes to transfer on this interrupt. */
 410         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
 411
 412         if (ireason & ATAPI_COD) {
 413                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
 414                 return ide_do_reset(drive);
 415         }
 416
 417         if (((ireason & ATAPI_IO) == ATAPI_IO) ==
 418                 !!(pc->flags & PC_FLAG_WRITING)) {
 419                 /* Hopefully, we will never get here */
 420                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
 421                                 "to %s!\n", drive->name,
 422                                 (ireason & ATAPI_IO) ? "Write" : "Read",
 423                                 (ireason & ATAPI_IO) ? "Read" : "Write");
 424                 return ide_do_reset(drive);
 425         }
 426
 427         if (!(pc->flags & PC_FLAG_WRITING)) {
 428                 /* Reading - Check that we have enough space */
 429                 temp = pc->xferred + bcount;
 430                 if (temp > pc->req_xfer) {
 431                         if (temp > pc->buf_size) {
 432                                 printk(KERN_ERR "%s: The device wants to send "
 433                                                 "us more data than expected - "
 434                                                 "discarding data\n",
 435                                                 drive->name);
 436                                 if (scsi)
 437                                         temp = pc->buf_size - pc->xferred;
 438                                 else
 439                                         temp = 0;
 440                                 if (temp) {
 441                                         if (pc->sg)
 442                                                 drive->pc_io_buffers(drive, pc,
 443                                                                      temp, 0);
 444                                         else
 445                                                 tp_ops->input_data(drive, NULL,
 446                                                         pc->cur_pos, temp);
 447                                         printk(KERN_ERR "%s: transferred %d of "
 448                                                         "%d bytes\n",
 449                                                         drive->name,
 450                                                         temp, bcount);
 451                                 }
 452                                 pc->xferred += temp;
 453                                 pc->cur_pos += temp;
 454                                 ide_pad_transfer(drive, 0, bcount - temp);
 455                                 goto next_irq;
 456                         }
 457                         debug_log("The device wants to send us more data than "
 458                                   "expected - allowing transfer\n");
 459                 }
 460                 xferfunc = tp_ops->input_data;
 461         } else
 462                 xferfunc = tp_ops->output_data;
 463
 464         if ((drive->media == ide_floppy && !scsi && !pc->buf) ||
 465             (drive->media == ide_tape && !scsi && pc->bh) ||
 466             (scsi && pc->sg)) {
 467                 int done = drive->pc_io_buffers(drive, pc, bcount,
 468                                   !!(pc->flags & PC_FLAG_WRITING));
 469
 470                 /* FIXME: don't do partial completions */
 471                 if (drive->media == ide_floppy && !scsi)
 472                         ide_end_request(drive, 1, done >> 9);
 473         } else
 474                 xferfunc(drive, NULL, pc->cur_pos, bcount);
 475
 476         /* Update the current position */
 477         pc->xferred += bcount;
 478         pc->cur_pos += bcount;
 479
 480         debug_log("[cmd %x] transferred %d bytes on that intr.\n",
 481                   rq->cmd[0], bcount);
 482 next_irq:
 483         /* And set the interrupt handler again */
 484         ide_set_handler(drive, ide_pc_intr, timeout, expiry);
 485         return ide_started;
 486 }
 487
 488 static u8 ide_read_ireason(ide_drive_t *drive)
 489 {
 490         ide_task_t task;
 491
 492         memset(&task, 0, sizeof(task));
 493         task.tf_flags = IDE_TFLAG_IN_NSECT;
 494
 495         drive->hwif->tp_ops->tf_read(drive, &task);
 496
 497         return task.tf.nsect & 3;
 498 }
 499
 500 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
 501 {
 502         int retries = 100;
 503
 504         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
 505                 (ireason & ATAPI_IO))) {
 506                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 507                                 "a packet command, retrying\n", drive->name);
 508                 udelay(100);
 509                 ireason = ide_read_ireason(drive);
 510                 if (retries == 0) {
 511                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 512                                         "a packet command, ignoring\n",
 513                                         drive->name);
 514                         ireason |= ATAPI_COD;
 515                         ireason &= ~ATAPI_IO;
 516                 }
 517         }
 518
 519         return ireason;
 520 }
 521
 522 static int ide_delayed_transfer_pc(ide_drive_t *drive)
 523 {
 524         /* Send the actual packet */
 525         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
 526
 527         /* Timeout for the packet command */
 528         return WAIT_FLOPPY_CMD;
 529 }
 530
 531 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 532 {
 533         struct ide_atapi_pc *pc = drive->pc;
 534         ide_hwif_t *hwif = drive->hwif;
 535         struct request *rq = hwif->hwgroup->rq;
 536         ide_expiry_t *expiry;
 537         unsigned int timeout;
 538         ide_startstop_t startstop;
 539         u8 ireason;
 540
 541         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
 542                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
 543                                 "DRQ isn't asserted\n", drive->name);
 544                 return startstop;
 545         }
 546
 547         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 548                 if (drive->dma)
 549                         drive->waiting_for_dma = 1;
 550         }
 551
 552         ireason = ide_read_ireason(drive);
 553         if (drive->media == ide_tape)
 554                 ireason = ide_wait_ireason(drive, ireason);
 555
 556         if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
 557                 printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
 558                                 "a packet command\n", drive->name);
 559                 return ide_do_reset(drive);
 560         }
 561
 562         /*
 563          * If necessary schedule the packet transfer to occur 'timeout'
 564          * miliseconds later in ide_delayed_transfer_pc() after the device
 565          * says it's ready for a packet.
 566          */
 567         if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
 568                 timeout = drive->pc_delay;
 569                 expiry = &ide_delayed_transfer_pc;
 570         } else {
 571                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 572                                                        : WAIT_TAPE_CMD;
 573                 expiry = NULL;
 574         }
 575
 576         /* Set the interrupt routine */
 577         ide_set_handler(drive, ide_pc_intr, timeout, expiry);
 578
 579         /* Begin DMA, if necessary */
 580         if (pc->flags & PC_FLAG_DMA_OK) {
 581                 pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
 582                 hwif->dma_ops->dma_start(drive);
 583         }
 584
 585         /* Send the actual packet */
 586         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
 587                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, 12);
 588
 589         return ide_started;
 590 }
 591
 592 ide_startstop_t ide_issue_pc(ide_drive_t *drive, unsigned int timeout)
 593 {
 594         struct ide_atapi_pc *pc = drive->pc;
 595         ide_hwif_t *hwif = drive->hwif;
 596         ide_expiry_t *expiry = NULL;
 597         u32 tf_flags;
 598         u16 bcount;
 599
 600         /* We haven't transferred any data yet */
 601         pc->xferred = 0;
 602         pc->cur_pos = pc->buf;
 603
 604         if (dev_is_idecd(drive)) {
 605                 tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
 606                 bcount = ide_cd_get_xferlen(hwif->hwgroup->rq);
 607                 expiry = ide_cd_expiry;
 608         } else {
 609                 tf_flags = IDE_TFLAG_OUT_DEVICE;
 610                 bcount = ((drive->media == ide_tape) ?
 611                                 pc->req_xfer :
 612                                 min(pc->req_xfer, 63 * 1024));
 613         }
 614
 615         if (pc->flags & PC_FLAG_DMA_ERROR) {
 616                 pc->flags &= ~PC_FLAG_DMA_ERROR;
 617                 ide_dma_off(drive);
 618         }
 619
 620         if (((pc->flags & PC_FLAG_DMA_OK) &&
 621                 (drive->dev_flags & IDE_DFLAG_USING_DMA)) ||
 622             drive->dma)
 623                 drive->dma = !hwif->dma_ops->dma_setup(drive);
 624
 625         if (!drive->dma)
 626                 pc->flags &= ~PC_FLAG_DMA_OK;
 627
 628         ide_pktcmd_tf_load(drive, tf_flags, bcount, drive->dma);
 629
 630         /* Issue the packet command */
 631         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 632                 if (drive->dma)
 633                         drive->waiting_for_dma = 0;
 634                 ide_execute_command(drive, ATA_CMD_PACKET, ide_transfer_pc,
 635                                     timeout, expiry);
 636                 return ide_started;
 637         } else {
 638                 ide_execute_pkt_cmd(drive);
 639                 return ide_transfer_pc(drive);
 640         }
 641 }
 642 EXPORT_SYMBOL_GPL(ide_issue_pc);