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.tf_flags = IDE_TFLAG_IN_LBAH | IDE_TFLAG_IN_LBAM |
 261                        IDE_TFLAG_IN_NSECT;
 262
 263         drive->hwif->tp_ops->tf_read(drive, &cmd);
 264
 265         *bcount = (cmd.tf.lbah << 8) | cmd.tf.lbam;
 266         *ireason = cmd.tf.nsect & 3;
 267 }
 268 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
 269
 270 /*
 271  * This is the usual interrupt handler which will be called during a packet
 272  * command.  We will transfer some of the data (as requested by the drive)
 273  * and will re-point interrupt handler to us.
 274  */
 275 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
 276 {
 277         struct ide_atapi_pc *pc = drive->pc;
 278         ide_hwif_t *hwif = drive->hwif;
 279         struct ide_cmd *cmd = &hwif->cmd;
 280         struct request *rq = hwif->rq;
 281         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 282         xfer_func_t *xferfunc;
 283         unsigned int timeout, done;
 284         u16 bcount;
 285         u8 stat, ireason, dsc = 0;
 286         u8 write = !!(pc->flags & PC_FLAG_WRITING);
 287
 288         debug_log("Enter %s - interrupt handler\n", __func__);
 289
 290         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 291                                                : WAIT_TAPE_CMD;
 292
 293         /* Clear the interrupt */
 294         stat = tp_ops->read_status(hwif);
 295
 296         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 297                 int rc;
 298
 299                 drive->waiting_for_dma = 0;
 300                 rc = hwif->dma_ops->dma_end(drive);
 301                 ide_dma_unmap_sg(drive, cmd);
 302
 303                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
 304                         if (drive->media == ide_floppy)
 305                                 printk(KERN_ERR "%s: DMA %s error\n",
 306                                         drive->name, rq_data_dir(pc->rq)
 307                                                      ? "write" : "read");
 308                         pc->flags |= PC_FLAG_DMA_ERROR;
 309                 } else {
 310                         pc->xferred = pc->req_xfer;
 311                         if (drive->pc_update_buffers)
 312                                 drive->pc_update_buffers(drive, pc);
 313                 }
 314                 debug_log("%s: DMA finished\n", drive->name);
 315         }
 316
 317         /* No more interrupts */
 318         if ((stat & ATA_DRQ) == 0) {
 319                 int uptodate, error;
 320                 unsigned int done;
 321
 322                 debug_log("Packet command completed, %d bytes transferred\n",
 323                           pc->xferred);
 324
 325                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 326
 327                 local_irq_enable_in_hardirq();
 328
 329                 if (drive->media == ide_tape &&
 330                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
 331                         stat &= ~ATA_ERR;
 332
 333                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
 334                         /* Error detected */
 335                         debug_log("%s: I/O error\n", drive->name);
 336
 337                         if (drive->media != ide_tape)
 338                                 pc->rq->errors++;
 339
 340                         if (rq->cmd[0] == REQUEST_SENSE) {
 341                                 printk(KERN_ERR "%s: I/O error in request sense"
 342                                                 " command\n", drive->name);
 343                                 return ide_do_reset(drive);
 344                         }
 345
 346                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
 347
 348                         /* Retry operation */
 349                         ide_retry_pc(drive, rq->rq_disk);
 350
 351                         /* queued, but not started */
 352                         return ide_stopped;
 353                 }
 354                 pc->error = 0;
 355
 356                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
 357                         dsc = 1;
 358
 359                 /* Command finished - Call the callback function */
 360                 uptodate = drive->pc_callback(drive, dsc);
 361
 362                 if (uptodate == 0)
 363                         drive->failed_pc = NULL;
 364
 365                 if (blk_special_request(rq)) {
 366                         rq->errors = 0;
 367                         done = blk_rq_bytes(rq);
 368                         error = 0;
 369                 } else {
 370
 371                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
 372                                 if (rq->errors == 0)
 373                                         rq->errors = -EIO;
 374                         }
 375
 376                         if (drive->media == ide_tape)
 377                                 done = ide_rq_bytes(rq); /* FIXME */
 378                         else
 379                                 done = blk_rq_bytes(rq);
 380
 381                         error = uptodate ? 0 : -EIO;
 382                 }
 383
 384                 ide_complete_rq(drive, error, done);
 385                 return ide_stopped;
 386         }
 387
 388         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 389                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 390                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
 391                                 "in DMA mode\n", drive->name);
 392                 ide_dma_off(drive);
 393                 return ide_do_reset(drive);
 394         }
 395
 396         /* Get the number of bytes to transfer on this interrupt. */
 397         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
 398
 399         if (ireason & ATAPI_COD) {
 400                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
 401                 return ide_do_reset(drive);
 402         }
 403
 404         if (((ireason & ATAPI_IO) == ATAPI_IO) == write) {
 405                 /* Hopefully, we will never get here */
 406                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
 407                                 "to %s!\n", drive->name,
 408                                 (ireason & ATAPI_IO) ? "Write" : "Read",
 409                                 (ireason & ATAPI_IO) ? "Read" : "Write");
 410                 return ide_do_reset(drive);
 411         }
 412
 413         xferfunc = write ? tp_ops->output_data : tp_ops->input_data;
 414
 415         if (drive->media == ide_floppy && pc->buf == NULL) {
 416                 done = min_t(unsigned int, bcount, cmd->nleft);
 417                 ide_pio_bytes(drive, cmd, write, done);
 418         } else if (drive->media == ide_tape && pc->bh) {
 419                 done = drive->pc_io_buffers(drive, pc, bcount, write);
 420         } else {
 421                 done = min_t(unsigned int, bcount, pc->req_xfer - pc->xferred);
 422                 xferfunc(drive, NULL, pc->cur_pos, done);
 423         }
 424
 425         /* Update the current position */
 426         pc->xferred += done;
 427         pc->cur_pos += done;
 428
 429         bcount -= done;
 430
 431         if (bcount)
 432                 ide_pad_transfer(drive, write, bcount);
 433
 434         debug_log("[cmd %x] transferred %d bytes, padded %d bytes\n",
 435                   rq->cmd[0], done, bcount);
 436
 437         /* And set the interrupt handler again */
 438         ide_set_handler(drive, ide_pc_intr, timeout);
 439         return ide_started;
 440 }
 441
 442 static void ide_init_packet_cmd(struct ide_cmd *cmd, u32 tf_flags,
 443                                 u16 bcount, u8 dma)
 444 {
 445         cmd->protocol  = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
 446         cmd->tf_flags |= IDE_TFLAG_OUT_LBAH | IDE_TFLAG_OUT_LBAM |
 447                          IDE_TFLAG_OUT_FEATURE | tf_flags;
 448         cmd->tf.command = ATA_CMD_PACKET;
 449         cmd->tf.feature = dma;          /* Use PIO/DMA */
 450         cmd->tf.lbam    = bcount & 0xff;
 451         cmd->tf.lbah    = (bcount >> 8) & 0xff;
 452 }
 453
 454 static u8 ide_read_ireason(ide_drive_t *drive)
 455 {
 456         struct ide_cmd cmd;
 457
 458         memset(&cmd, 0, sizeof(cmd));
 459         cmd.tf_flags = IDE_TFLAG_IN_NSECT;
 460
 461         drive->hwif->tp_ops->tf_read(drive, &cmd);
 462
 463         return cmd.tf.nsect & 3;
 464 }
 465
 466 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
 467 {
 468         int retries = 100;
 469
 470         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
 471                 (ireason & ATAPI_IO))) {
 472                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 473                                 "a packet command, retrying\n", drive->name);
 474                 udelay(100);
 475                 ireason = ide_read_ireason(drive);
 476                 if (retries == 0) {
 477                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 478                                         "a packet command, ignoring\n",
 479                                         drive->name);
 480                         ireason |= ATAPI_COD;
 481                         ireason &= ~ATAPI_IO;
 482                 }
 483         }
 484
 485         return ireason;
 486 }
 487
 488 static int ide_delayed_transfer_pc(ide_drive_t *drive)
 489 {
 490         /* Send the actual packet */
 491         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
 492
 493         /* Timeout for the packet command */
 494         return WAIT_FLOPPY_CMD;
 495 }
 496
 497 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 498 {
 499         struct ide_atapi_pc *uninitialized_var(pc);
 500         ide_hwif_t *hwif = drive->hwif;
 501         struct request *rq = hwif->rq;
 502         ide_expiry_t *expiry;
 503         unsigned int timeout;
 504         int cmd_len;
 505         ide_startstop_t startstop;
 506         u8 ireason;
 507
 508         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
 509                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
 510                                 "DRQ isn't asserted\n", drive->name);
 511                 return startstop;
 512         }
 513
 514         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 515                 if (drive->dma)
 516                         drive->waiting_for_dma = 1;
 517         }
 518
 519         if (dev_is_idecd(drive)) {
 520                 /* ATAPI commands get padded out to 12 bytes minimum */
 521                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
 522                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
 523                         cmd_len = ATAPI_MIN_CDB_BYTES;
 524
 525                 timeout = rq->timeout;
 526                 expiry  = ide_cd_expiry;
 527         } else {
 528                 pc = drive->pc;
 529
 530                 cmd_len = ATAPI_MIN_CDB_BYTES;
 531
 532                 /*
 533                  * If necessary schedule the packet transfer to occur 'timeout'
 534                  * miliseconds later in ide_delayed_transfer_pc() after the
 535                  * device says it's ready for a packet.
 536                  */
 537                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
 538                         timeout = drive->pc_delay;
 539                         expiry = &ide_delayed_transfer_pc;
 540                 } else {
 541                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 542                                                                : WAIT_TAPE_CMD;
 543                         expiry = NULL;
 544                 }
 545
 546                 ireason = ide_read_ireason(drive);
 547                 if (drive->media == ide_tape)
 548                         ireason = ide_wait_ireason(drive, ireason);
 549
 550                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
 551                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
 552                                         "a packet command\n", drive->name);
 553
 554                         return ide_do_reset(drive);
 555                 }
 556         }
 557
 558         hwif->expiry = expiry;
 559
 560         /* Set the interrupt routine */
 561         ide_set_handler(drive,
 562                         (dev_is_idecd(drive) ? drive->irq_handler
 563                                              : ide_pc_intr),
 564                         timeout);
 565
 566         /* Send the actual packet */
 567         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
 568                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
 569
 570         /* Begin DMA, if necessary */
 571         if (dev_is_idecd(drive)) {
 572                 if (drive->dma)
 573                         hwif->dma_ops->dma_start(drive);
 574         } else {
 575                 if (pc->flags & PC_FLAG_DMA_OK) {
 576                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
 577                         hwif->dma_ops->dma_start(drive);
 578                 }
 579         }
 580
 581         return ide_started;
 582 }
 583
 584 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
 585 {
 586         struct ide_atapi_pc *pc;
 587         ide_hwif_t *hwif = drive->hwif;
 588         ide_expiry_t *expiry = NULL;
 589         struct request *rq = hwif->rq;
 590         unsigned int timeout;
 591         u32 tf_flags;
 592         u16 bcount;
 593         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
 594
 595         if (dev_is_idecd(drive)) {
 596                 tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
 597                 bcount = ide_cd_get_xferlen(rq);
 598                 expiry = ide_cd_expiry;
 599                 timeout = ATAPI_WAIT_PC;
 600
 601                 if (drive->dma)
 602                         drive->dma = !ide_dma_prepare(drive, cmd);
 603         } else {
 604                 pc = drive->pc;
 605
 606                 /* We haven't transferred any data yet */
 607                 pc->xferred = 0;
 608                 pc->cur_pos = pc->buf;
 609
 610                 tf_flags = IDE_TFLAG_OUT_DEVICE;
 611                 bcount = ((drive->media == ide_tape) ?
 612                                 pc->req_xfer :
 613                                 min(pc->req_xfer, 63 * 1024));
 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->dma = !ide_dma_prepare(drive, cmd);
 622
 623                 if (!drive->dma)
 624                         pc->flags &= ~PC_FLAG_DMA_OK;
 625
 626                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 627                                                        : WAIT_TAPE_CMD;
 628         }
 629
 630         ide_init_packet_cmd(cmd, tf_flags, bcount, drive->dma);
 631
 632         (void)do_rw_taskfile(drive, cmd);
 633
 634         if (drq_int) {
 635                 if (drive->dma)
 636                         drive->waiting_for_dma = 0;
 637                 hwif->expiry = expiry;
 638         }
 639
 640         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
 641
 642         return drq_int ? ide_started : ide_transfer_pc(drive);
 643 }
 644 EXPORT_SYMBOL_GPL(ide_issue_pc);