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