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 #define ATAPI_MIN_CDB_BYTES     12
  19
  20 static inline int dev_is_idecd(ide_drive_t *drive)
  21 {
  22         return drive->media == ide_cdrom || drive->media == ide_optical;
  23 }
  24
  25 /*
  26  * Check whether we can support a device,
  27  * based on the ATAPI IDENTIFY command results.
  28  */
  29 int ide_check_atapi_device(ide_drive_t *drive, const char *s)
  30 {
  31         u16 *id = drive->id;
  32         u8 gcw[2], protocol, device_type, removable, drq_type, packet_size;
  33
  34         *((u16 *)&gcw) = id[ATA_ID_CONFIG];
  35
  36         protocol    = (gcw[1] & 0xC0) >> 6;
  37         device_type =  gcw[1] & 0x1F;
  38         removable   = (gcw[0] & 0x80) >> 7;
  39         drq_type    = (gcw[0] & 0x60) >> 5;
  40         packet_size =  gcw[0] & 0x03;
  41
  42 #ifdef CONFIG_PPC
  43         /* kludge for Apple PowerBook internal zip */
  44         if (drive->media == ide_floppy && device_type == 5 &&
  45             !strstr((char *)&id[ATA_ID_PROD], "CD-ROM") &&
  46             strstr((char *)&id[ATA_ID_PROD], "ZIP"))
  47                 device_type = 0;
  48 #endif
  49
  50         if (protocol != 2)
  51                 printk(KERN_ERR "%s: %s: protocol (0x%02x) is not ATAPI\n",
  52                         s, drive->name, protocol);
  53         else if ((drive->media == ide_floppy && device_type != 0) ||
  54                  (drive->media == ide_tape && device_type != 1))
  55                 printk(KERN_ERR "%s: %s: invalid device type (0x%02x)\n",
  56                         s, drive->name, device_type);
  57         else if (removable == 0)
  58                 printk(KERN_ERR "%s: %s: the removable flag is not set\n",
  59                         s, drive->name);
  60         else if (drive->media == ide_floppy && drq_type == 3)
  61                 printk(KERN_ERR "%s: %s: sorry, DRQ type (0x%02x) not "
  62                         "supported\n", s, drive->name, drq_type);
  63         else if (packet_size != 0)
  64                 printk(KERN_ERR "%s: %s: packet size (0x%02x) is not 12 "
  65                         "bytes\n", s, drive->name, packet_size);
  66         else
  67                 return 1;
  68         return 0;
  69 }
  70 EXPORT_SYMBOL_GPL(ide_check_atapi_device);
  71
  72 /* PIO data transfer routine using the scatter gather table. */
  73 int ide_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
  74                     unsigned int bcount, int write)
  75 {
  76         ide_hwif_t *hwif = drive->hwif;
  77         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
  78         xfer_func_t *xf = write ? tp_ops->output_data : tp_ops->input_data;
  79         struct scatterlist *sg = pc->sg;
  80         char *buf;
  81         int count, done = 0;
  82
  83         while (bcount) {
  84                 count = min(sg->length - pc->b_count, bcount);
  85
  86                 if (PageHighMem(sg_page(sg))) {
  87                         unsigned long flags;
  88
  89                         local_irq_save(flags);
  90                         buf = kmap_atomic(sg_page(sg), KM_IRQ0) + sg->offset;
  91                         xf(drive, NULL, buf + pc->b_count, count);
  92                         kunmap_atomic(buf - sg->offset, KM_IRQ0);
  93                         local_irq_restore(flags);
  94                 } else {
  95                         buf = sg_virt(sg);
  96                         xf(drive, NULL, buf + pc->b_count, count);
  97                 }
  98
  99                 bcount -= count;
 100                 pc->b_count += count;
 101                 done += count;
 102
 103                 if (pc->b_count == sg->length) {
 104                         if (!--pc->sg_cnt)
 105                                 break;
 106                         pc->sg = sg = sg_next(sg);
 107                         pc->b_count = 0;
 108                 }
 109         }
 110
 111         if (bcount) {
 112                 printk(KERN_ERR "%s: %d leftover bytes, %s\n", drive->name,
 113                         bcount, write ? "padding with zeros"
 114                                       : "discarding data");
 115                 ide_pad_transfer(drive, write, bcount);
 116         }
 117
 118         return done;
 119 }
 120 EXPORT_SYMBOL_GPL(ide_io_buffers);
 121
 122 void ide_init_pc(struct ide_atapi_pc *pc)
 123 {
 124         memset(pc, 0, sizeof(*pc));
 125         pc->buf = pc->pc_buf;
 126         pc->buf_size = IDE_PC_BUFFER_SIZE;
 127 }
 128 EXPORT_SYMBOL_GPL(ide_init_pc);
 129
 130 /*
 131  * Generate a new packet command request in front of the request queue, before
 132  * the current request, so that it will be processed immediately, on the next
 133  * pass through the driver.
 134  */
 135 static void ide_queue_pc_head(ide_drive_t *drive, struct gendisk *disk,
 136                               struct ide_atapi_pc *pc, struct request *rq)
 137 {
 138         blk_rq_init(NULL, rq);
 139         rq->cmd_type = REQ_TYPE_SPECIAL;
 140         rq->cmd_flags |= REQ_PREEMPT;
 141         rq->buffer = (char *)pc;
 142         rq->rq_disk = disk;
 143
 144         if (pc->req_xfer) {
 145                 rq->data = pc->buf;
 146                 rq->data_len = pc->req_xfer;
 147         }
 148
 149         memcpy(rq->cmd, pc->c, 12);
 150         if (drive->media == ide_tape)
 151                 rq->cmd[13] = REQ_IDETAPE_PC1;
 152         ide_do_drive_cmd(drive, rq);
 153 }
 154
 155 /*
 156  * Add a special packet command request to the tail of the request queue,
 157  * and wait for it to be serviced.
 158  */
 159 int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,
 160                       struct ide_atapi_pc *pc)
 161 {
 162         struct request *rq;
 163         int error;
 164
 165         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
 166         rq->cmd_type = REQ_TYPE_SPECIAL;
 167         rq->buffer = (char *)pc;
 168
 169         if (pc->req_xfer) {
 170                 rq->data = pc->buf;
 171                 rq->data_len = pc->req_xfer;
 172         }
 173
 174         memcpy(rq->cmd, pc->c, 12);
 175         if (drive->media == ide_tape)
 176                 rq->cmd[13] = REQ_IDETAPE_PC1;
 177         error = blk_execute_rq(drive->queue, disk, rq, 0);
 178         blk_put_request(rq);
 179
 180         return error;
 181 }
 182 EXPORT_SYMBOL_GPL(ide_queue_pc_tail);
 183
 184 int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
 185 {
 186         struct ide_atapi_pc pc;
 187
 188         ide_init_pc(&pc);
 189         pc.c[0] = TEST_UNIT_READY;
 190
 191         return ide_queue_pc_tail(drive, disk, &pc);
 192 }
 193 EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);
 194
 195 int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
 196 {
 197         struct ide_atapi_pc pc;
 198
 199         ide_init_pc(&pc);
 200         pc.c[0] = START_STOP;
 201         pc.c[4] = start;
 202
 203         if (drive->media == ide_tape)
 204                 pc.flags |= PC_FLAG_WAIT_FOR_DSC;
 205
 206         return ide_queue_pc_tail(drive, disk, &pc);
 207 }
 208 EXPORT_SYMBOL_GPL(ide_do_start_stop);
 209
 210 int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
 211 {
 212         struct ide_atapi_pc pc;
 213
 214         if ((drive->dev_flags & IDE_DFLAG_DOORLOCKING) == 0)
 215                 return 0;
 216
 217         ide_init_pc(&pc);
 218         pc.c[0] = ALLOW_MEDIUM_REMOVAL;
 219         pc.c[4] = on;
 220
 221         return ide_queue_pc_tail(drive, disk, &pc);
 222 }
 223 EXPORT_SYMBOL_GPL(ide_set_media_lock);
 224
 225 void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
 226 {
 227         ide_init_pc(pc);
 228         pc->c[0] = REQUEST_SENSE;
 229         if (drive->media == ide_floppy) {
 230                 pc->c[4] = 255;
 231                 pc->req_xfer = 18;
 232         } else {
 233                 pc->c[4] = 20;
 234                 pc->req_xfer = 20;
 235         }
 236 }
 237 EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);
 238
 239 /*
 240  * Called when an error was detected during the last packet command.
 241  * We queue a request sense packet command in the head of the request list.
 242  */
 243 void ide_retry_pc(ide_drive_t *drive, struct gendisk *disk)
 244 {
 245         struct request *rq = &drive->request_sense_rq;
 246         struct ide_atapi_pc *pc = &drive->request_sense_pc;
 247
 248         (void)ide_read_error(drive);
 249         ide_create_request_sense_cmd(drive, pc);
 250         if (drive->media == ide_tape)
 251                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
 252         ide_queue_pc_head(drive, disk, pc, rq);
 253 }
 254 EXPORT_SYMBOL_GPL(ide_retry_pc);
 255
 256 int ide_cd_expiry(ide_drive_t *drive)
 257 {
 258         struct request *rq = drive->hwif->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->rq;
 310         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 311         xfer_func_t *xferfunc;
 312         unsigned int timeout, temp;
 313         u16 bcount;
 314         u8 stat, ireason, dsc = 0;
 315
 316         debug_log("Enter %s - interrupt handler\n", __func__);
 317
 318         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 319                                                : WAIT_TAPE_CMD;
 320
 321         if (pc->flags & PC_FLAG_TIMEDOUT) {
 322                 drive->pc_callback(drive, 0);
 323                 return ide_stopped;
 324         }
 325
 326         /* Clear the interrupt */
 327         stat = tp_ops->read_status(hwif);
 328
 329         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 330                 if (hwif->dma_ops->dma_end(drive) ||
 331                     (drive->media == ide_tape && (stat & ATA_ERR))) {
 332                         if (drive->media == ide_floppy)
 333                                 printk(KERN_ERR "%s: DMA %s error\n",
 334                                         drive->name, rq_data_dir(pc->rq)
 335                                                      ? "write" : "read");
 336                         pc->flags |= PC_FLAG_DMA_ERROR;
 337                 } else {
 338                         pc->xferred = pc->req_xfer;
 339                         if (drive->pc_update_buffers)
 340                                 drive->pc_update_buffers(drive, pc);
 341                 }
 342                 debug_log("%s: DMA finished\n", drive->name);
 343         }
 344
 345         /* No more interrupts */
 346         if ((stat & ATA_DRQ) == 0) {
 347                 debug_log("Packet command completed, %d bytes transferred\n",
 348                           pc->xferred);
 349
 350                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 351
 352                 local_irq_enable_in_hardirq();
 353
 354                 if (drive->media == ide_tape &&
 355                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
 356                         stat &= ~ATA_ERR;
 357
 358                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
 359                         /* Error detected */
 360                         debug_log("%s: I/O error\n", drive->name);
 361
 362                         if (drive->media != ide_tape)
 363                                 pc->rq->errors++;
 364
 365                         if (rq->cmd[0] == REQUEST_SENSE) {
 366                                 printk(KERN_ERR "%s: I/O error in request sense"
 367                                                 " command\n", drive->name);
 368                                 return ide_do_reset(drive);
 369                         }
 370
 371                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
 372
 373                         /* Retry operation */
 374                         ide_retry_pc(drive, rq->rq_disk);
 375
 376                         /* queued, but not started */
 377                         return ide_stopped;
 378                 }
 379                 pc->error = 0;
 380
 381                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
 382                         dsc = 1;
 383
 384                 /* Command finished - Call the callback function */
 385                 drive->pc_callback(drive, dsc);
 386
 387                 return ide_stopped;
 388         }
 389
 390         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 391                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 392                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
 393                                 "in DMA mode\n", drive->name);
 394                 ide_dma_off(drive);
 395                 return ide_do_reset(drive);
 396         }
 397
 398         /* Get the number of bytes to transfer on this interrupt. */
 399         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
 400
 401         if (ireason & ATAPI_COD) {
 402                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
 403                 return ide_do_reset(drive);
 404         }
 405
 406         if (((ireason & ATAPI_IO) == ATAPI_IO) ==
 407                 !!(pc->flags & PC_FLAG_WRITING)) {
 408                 /* Hopefully, we will never get here */
 409                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
 410                                 "to %s!\n", drive->name,
 411                                 (ireason & ATAPI_IO) ? "Write" : "Read",
 412                                 (ireason & ATAPI_IO) ? "Read" : "Write");
 413                 return ide_do_reset(drive);
 414         }
 415
 416         if (!(pc->flags & PC_FLAG_WRITING)) {
 417                 /* Reading - Check that we have enough space */
 418                 temp = pc->xferred + bcount;
 419                 if (temp > pc->req_xfer) {
 420                         if (temp > pc->buf_size) {
 421                                 printk(KERN_ERR "%s: The device wants to send "
 422                                                 "us more data than expected - "
 423                                                 "discarding data\n",
 424                                                 drive->name);
 425
 426                                 ide_pad_transfer(drive, 0, bcount);
 427                                 goto next_irq;
 428                         }
 429                         debug_log("The device wants to send us more data than "
 430                                   "expected - allowing transfer\n");
 431                 }
 432                 xferfunc = tp_ops->input_data;
 433         } else
 434                 xferfunc = tp_ops->output_data;
 435
 436         if ((drive->media == ide_floppy && !pc->buf) ||
 437             (drive->media == ide_tape && pc->bh)) {
 438                 int done = drive->pc_io_buffers(drive, pc, bcount,
 439                                   !!(pc->flags & PC_FLAG_WRITING));
 440
 441                 /* FIXME: don't do partial completions */
 442                 if (drive->media == ide_floppy)
 443                         ide_end_request(drive, 1, done >> 9);
 444         } else
 445                 xferfunc(drive, NULL, pc->cur_pos, bcount);
 446
 447         /* Update the current position */
 448         pc->xferred += bcount;
 449         pc->cur_pos += bcount;
 450
 451         debug_log("[cmd %x] transferred %d bytes on that intr.\n",
 452                   rq->cmd[0], bcount);
 453 next_irq:
 454         /* And set the interrupt handler again */
 455         ide_set_handler(drive, ide_pc_intr, timeout, NULL);
 456         return ide_started;
 457 }
 458
 459 static u8 ide_read_ireason(ide_drive_t *drive)
 460 {
 461         ide_task_t task;
 462
 463         memset(&task, 0, sizeof(task));
 464         task.tf_flags = IDE_TFLAG_IN_NSECT;
 465
 466         drive->hwif->tp_ops->tf_read(drive, &task);
 467
 468         return task.tf.nsect & 3;
 469 }
 470
 471 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
 472 {
 473         int retries = 100;
 474
 475         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
 476                 (ireason & ATAPI_IO))) {
 477                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 478                                 "a packet command, retrying\n", drive->name);
 479                 udelay(100);
 480                 ireason = ide_read_ireason(drive);
 481                 if (retries == 0) {
 482                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 483                                         "a packet command, ignoring\n",
 484                                         drive->name);
 485                         ireason |= ATAPI_COD;
 486                         ireason &= ~ATAPI_IO;
 487                 }
 488         }
 489
 490         return ireason;
 491 }
 492
 493 static int ide_delayed_transfer_pc(ide_drive_t *drive)
 494 {
 495         /* Send the actual packet */
 496         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
 497
 498         /* Timeout for the packet command */
 499         return WAIT_FLOPPY_CMD;
 500 }
 501
 502 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 503 {
 504         struct ide_atapi_pc *uninitialized_var(pc);
 505         ide_hwif_t *hwif = drive->hwif;
 506         struct request *rq = hwif->rq;
 507         ide_expiry_t *expiry;
 508         unsigned int timeout;
 509         int cmd_len;
 510         ide_startstop_t startstop;
 511         u8 ireason;
 512
 513         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
 514                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
 515                                 "DRQ isn't asserted\n", drive->name);
 516                 return startstop;
 517         }
 518
 519         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 520                 if (drive->dma)
 521                         drive->waiting_for_dma = 1;
 522         }
 523
 524         if (dev_is_idecd(drive)) {
 525                 /* ATAPI commands get padded out to 12 bytes minimum */
 526                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
 527                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
 528                         cmd_len = ATAPI_MIN_CDB_BYTES;
 529
 530                 timeout = rq->timeout;
 531                 expiry  = ide_cd_expiry;
 532         } else {
 533                 pc = drive->pc;
 534
 535                 cmd_len = ATAPI_MIN_CDB_BYTES;
 536
 537                 /*
 538                  * If necessary schedule the packet transfer to occur 'timeout'
 539                  * miliseconds later in ide_delayed_transfer_pc() after the
 540                  * device says it's ready for a packet.
 541                  */
 542                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
 543                         timeout = drive->pc_delay;
 544                         expiry = &ide_delayed_transfer_pc;
 545                 } else {
 546                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 547                                                                : WAIT_TAPE_CMD;
 548                         expiry = NULL;
 549                 }
 550
 551                 ireason = ide_read_ireason(drive);
 552                 if (drive->media == ide_tape)
 553                         ireason = ide_wait_ireason(drive, ireason);
 554
 555                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
 556                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
 557                                         "a packet command\n", drive->name);
 558
 559                         return ide_do_reset(drive);
 560                 }
 561         }
 562
 563         /* Set the interrupt routine */
 564         ide_set_handler(drive,
 565                         (dev_is_idecd(drive) ? drive->irq_handler
 566                                              : ide_pc_intr),
 567                         timeout, expiry);
 568
 569         /* Begin DMA, if necessary */
 570         if (dev_is_idecd(drive)) {
 571                 if (drive->dma)
 572                         hwif->dma_ops->dma_start(drive);
 573         } else {
 574                 if (pc->flags & PC_FLAG_DMA_OK) {
 575                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
 576                         hwif->dma_ops->dma_start(drive);
 577                 }
 578         }
 579
 580         /* Send the actual packet */
 581         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
 582                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
 583
 584         return ide_started;
 585 }
 586
 587 ide_startstop_t ide_issue_pc(ide_drive_t *drive)
 588 {
 589         struct ide_atapi_pc *pc;
 590         ide_hwif_t *hwif = drive->hwif;
 591         ide_expiry_t *expiry = NULL;
 592         unsigned int timeout;
 593         u32 tf_flags;
 594         u16 bcount;
 595
 596         if (dev_is_idecd(drive)) {
 597                 tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
 598                 bcount = ide_cd_get_xferlen(hwif->rq);
 599                 expiry = ide_cd_expiry;
 600                 timeout = ATAPI_WAIT_PC;
 601
 602                 if (drive->dma)
 603                         drive->dma = !hwif->dma_ops->dma_setup(drive);
 604         } else {
 605                 pc = drive->pc;
 606
 607                 /* We haven't transferred any data yet */
 608                 pc->xferred = 0;
 609                 pc->cur_pos = pc->buf;
 610
 611                 tf_flags = IDE_TFLAG_OUT_DEVICE;
 612                 bcount = ((drive->media == ide_tape) ?
 613                                 pc->req_xfer :
 614                                 min(pc->req_xfer, 63 * 1024));
 615
 616                 if (pc->flags & PC_FLAG_DMA_ERROR) {
 617                         pc->flags &= ~PC_FLAG_DMA_ERROR;
 618                         ide_dma_off(drive);
 619                 }
 620
 621                 if ((pc->flags & PC_FLAG_DMA_OK) &&
 622                      (drive->dev_flags & IDE_DFLAG_USING_DMA))
 623                         drive->dma = !hwif->dma_ops->dma_setup(drive);
 624
 625                 if (!drive->dma)
 626                         pc->flags &= ~PC_FLAG_DMA_OK;
 627
 628                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 629                                                        : WAIT_TAPE_CMD;
 630         }
 631
 632         ide_pktcmd_tf_load(drive, tf_flags, bcount, drive->dma);
 633
 634         /* Issue the packet command */
 635         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 636                 if (drive->dma)
 637                         drive->waiting_for_dma = 0;
 638                 ide_execute_command(drive, ATA_CMD_PACKET, ide_transfer_pc,
 639                                     timeout, expiry);
 640                 return ide_started;
 641         } else {
 642                 ide_execute_pkt_cmd(drive);
 643                 return ide_transfer_pc(drive);
 644         }
 645 }
 646 EXPORT_SYMBOL_GPL(ide_issue_pc);