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