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_taskfile tf;
 258
 259         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT |
 260                                      IDE_VALID_LBAM | IDE_VALID_LBAH);
 261
 262         *bcount = (tf.lbah << 8) | tf.lbam;
 263         *ireason = tf.nsect & 3;
 264 }
 265 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
 266
 267 /*
 268  * This is the usual interrupt handler which will be called during a packet
 269  * command.  We will transfer some of the data (as requested by the drive)
 270  * and will re-point interrupt handler to us.
 271  */
 272 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
 273 {
 274         struct ide_atapi_pc *pc = drive->pc;
 275         ide_hwif_t *hwif = drive->hwif;
 276         struct ide_cmd *cmd = &hwif->cmd;
 277         struct request *rq = hwif->rq;
 278         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
 279         xfer_func_t *xferfunc;
 280         unsigned int timeout, done;
 281         u16 bcount;
 282         u8 stat, ireason, dsc = 0;
 283         u8 write = !!(pc->flags & PC_FLAG_WRITING);
 284
 285         debug_log("Enter %s - interrupt handler\n", __func__);
 286
 287         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 288                                                : WAIT_TAPE_CMD;
 289
 290         /* Clear the interrupt */
 291         stat = tp_ops->read_status(hwif);
 292
 293         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 294                 int rc;
 295
 296                 drive->waiting_for_dma = 0;
 297                 rc = hwif->dma_ops->dma_end(drive);
 298                 ide_dma_unmap_sg(drive, cmd);
 299
 300                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
 301                         if (drive->media == ide_floppy)
 302                                 printk(KERN_ERR "%s: DMA %s error\n",
 303                                         drive->name, rq_data_dir(pc->rq)
 304                                                      ? "write" : "read");
 305                         pc->flags |= PC_FLAG_DMA_ERROR;
 306                 } else {
 307                         pc->xferred = pc->req_xfer;
 308                         if (drive->pc_update_buffers)
 309                                 drive->pc_update_buffers(drive, pc);
 310                 }
 311                 debug_log("%s: DMA finished\n", drive->name);
 312         }
 313
 314         /* No more interrupts */
 315         if ((stat & ATA_DRQ) == 0) {
 316                 int uptodate, error;
 317                 unsigned int done;
 318
 319                 debug_log("Packet command completed, %d bytes transferred\n",
 320                           pc->xferred);
 321
 322                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 323
 324                 local_irq_enable_in_hardirq();
 325
 326                 if (drive->media == ide_tape &&
 327                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
 328                         stat &= ~ATA_ERR;
 329
 330                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
 331                         /* Error detected */
 332                         debug_log("%s: I/O error\n", drive->name);
 333
 334                         if (drive->media != ide_tape)
 335                                 pc->rq->errors++;
 336
 337                         if (rq->cmd[0] == REQUEST_SENSE) {
 338                                 printk(KERN_ERR "%s: I/O error in request sense"
 339                                                 " command\n", drive->name);
 340                                 return ide_do_reset(drive);
 341                         }
 342
 343                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
 344
 345                         /* Retry operation */
 346                         ide_retry_pc(drive, rq->rq_disk);
 347
 348                         /* queued, but not started */
 349                         return ide_stopped;
 350                 }
 351                 pc->error = 0;
 352
 353                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
 354                         dsc = 1;
 355
 356                 /* Command finished - Call the callback function */
 357                 uptodate = drive->pc_callback(drive, dsc);
 358
 359                 if (uptodate == 0)
 360                         drive->failed_pc = NULL;
 361
 362                 if (blk_special_request(rq)) {
 363                         rq->errors = 0;
 364                         done = blk_rq_bytes(rq);
 365                         error = 0;
 366                 } else {
 367
 368                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
 369                                 if (rq->errors == 0)
 370                                         rq->errors = -EIO;
 371                         }
 372
 373                         if (drive->media == ide_tape)
 374                                 done = ide_rq_bytes(rq); /* FIXME */
 375                         else
 376                                 done = blk_rq_bytes(rq);
 377
 378                         error = uptodate ? 0 : -EIO;
 379                 }
 380
 381                 ide_complete_rq(drive, error, done);
 382                 return ide_stopped;
 383         }
 384
 385         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
 386                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
 387                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
 388                                 "in DMA mode\n", drive->name);
 389                 ide_dma_off(drive);
 390                 return ide_do_reset(drive);
 391         }
 392
 393         /* Get the number of bytes to transfer on this interrupt. */
 394         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
 395
 396         if (ireason & ATAPI_COD) {
 397                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
 398                 return ide_do_reset(drive);
 399         }
 400
 401         if (((ireason & ATAPI_IO) == ATAPI_IO) == write) {
 402                 /* Hopefully, we will never get here */
 403                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
 404                                 "to %s!\n", drive->name,
 405                                 (ireason & ATAPI_IO) ? "Write" : "Read",
 406                                 (ireason & ATAPI_IO) ? "Read" : "Write");
 407                 return ide_do_reset(drive);
 408         }
 409
 410         xferfunc = write ? tp_ops->output_data : tp_ops->input_data;
 411
 412         if (drive->media == ide_floppy && pc->buf == NULL) {
 413                 done = min_t(unsigned int, bcount, cmd->nleft);
 414                 ide_pio_bytes(drive, cmd, write, done);
 415         } else if (drive->media == ide_tape && pc->bh) {
 416                 done = drive->pc_io_buffers(drive, pc, bcount, write);
 417         } else {
 418                 done = min_t(unsigned int, bcount, pc->req_xfer - pc->xferred);
 419                 xferfunc(drive, NULL, pc->cur_pos, done);
 420         }
 421
 422         /* Update the current position */
 423         pc->xferred += done;
 424         pc->cur_pos += done;
 425
 426         bcount -= done;
 427
 428         if (bcount)
 429                 ide_pad_transfer(drive, write, bcount);
 430
 431         debug_log("[cmd %x] transferred %d bytes, padded %d bytes\n",
 432                   rq->cmd[0], done, bcount);
 433
 434         /* And set the interrupt handler again */
 435         ide_set_handler(drive, ide_pc_intr, timeout);
 436         return ide_started;
 437 }
 438
 439 static void ide_init_packet_cmd(struct ide_cmd *cmd, u8 valid_tf,
 440                                 u16 bcount, u8 dma)
 441 {
 442         cmd->protocol = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
 443         cmd->valid.out.tf = IDE_VALID_LBAH | IDE_VALID_LBAM |
 444                             IDE_VALID_FEATURE | valid_tf;
 445         cmd->tf.command = ATA_CMD_PACKET;
 446         cmd->tf.feature = dma;          /* Use PIO/DMA */
 447         cmd->tf.lbam    = bcount & 0xff;
 448         cmd->tf.lbah    = (bcount >> 8) & 0xff;
 449 }
 450
 451 static u8 ide_read_ireason(ide_drive_t *drive)
 452 {
 453         struct ide_taskfile tf;
 454
 455         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT);
 456
 457         return tf.nsect & 3;
 458 }
 459
 460 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
 461 {
 462         int retries = 100;
 463
 464         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
 465                 (ireason & ATAPI_IO))) {
 466                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 467                                 "a packet command, retrying\n", drive->name);
 468                 udelay(100);
 469                 ireason = ide_read_ireason(drive);
 470                 if (retries == 0) {
 471                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
 472                                         "a packet command, ignoring\n",
 473                                         drive->name);
 474                         ireason |= ATAPI_COD;
 475                         ireason &= ~ATAPI_IO;
 476                 }
 477         }
 478
 479         return ireason;
 480 }
 481
 482 static int ide_delayed_transfer_pc(ide_drive_t *drive)
 483 {
 484         /* Send the actual packet */
 485         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
 486
 487         /* Timeout for the packet command */
 488         return WAIT_FLOPPY_CMD;
 489 }
 490
 491 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
 492 {
 493         struct ide_atapi_pc *uninitialized_var(pc);
 494         ide_hwif_t *hwif = drive->hwif;
 495         struct request *rq = hwif->rq;
 496         ide_expiry_t *expiry;
 497         unsigned int timeout;
 498         int cmd_len;
 499         ide_startstop_t startstop;
 500         u8 ireason;
 501
 502         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
 503                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
 504                                 "DRQ isn't asserted\n", drive->name);
 505                 return startstop;
 506         }
 507
 508         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
 509                 if (drive->dma)
 510                         drive->waiting_for_dma = 1;
 511         }
 512
 513         if (dev_is_idecd(drive)) {
 514                 /* ATAPI commands get padded out to 12 bytes minimum */
 515                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
 516                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
 517                         cmd_len = ATAPI_MIN_CDB_BYTES;
 518
 519                 timeout = rq->timeout;
 520                 expiry  = ide_cd_expiry;
 521         } else {
 522                 pc = drive->pc;
 523
 524                 cmd_len = ATAPI_MIN_CDB_BYTES;
 525
 526                 /*
 527                  * If necessary schedule the packet transfer to occur 'timeout'
 528                  * miliseconds later in ide_delayed_transfer_pc() after the
 529                  * device says it's ready for a packet.
 530                  */
 531                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
 532                         timeout = drive->pc_delay;
 533                         expiry = &ide_delayed_transfer_pc;
 534                 } else {
 535                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 536                                                                : WAIT_TAPE_CMD;
 537                         expiry = NULL;
 538                 }
 539
 540                 ireason = ide_read_ireason(drive);
 541                 if (drive->media == ide_tape)
 542                         ireason = ide_wait_ireason(drive, ireason);
 543
 544                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
 545                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
 546                                         "a packet command\n", drive->name);
 547
 548                         return ide_do_reset(drive);
 549                 }
 550         }
 551
 552         hwif->expiry = expiry;
 553
 554         /* Set the interrupt routine */
 555         ide_set_handler(drive,
 556                         (dev_is_idecd(drive) ? drive->irq_handler
 557                                              : ide_pc_intr),
 558                         timeout);
 559
 560         /* Send the actual packet */
 561         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
 562                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
 563
 564         /* Begin DMA, if necessary */
 565         if (dev_is_idecd(drive)) {
 566                 if (drive->dma)
 567                         hwif->dma_ops->dma_start(drive);
 568         } else {
 569                 if (pc->flags & PC_FLAG_DMA_OK) {
 570                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
 571                         hwif->dma_ops->dma_start(drive);
 572                 }
 573         }
 574
 575         return ide_started;
 576 }
 577
 578 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
 579 {
 580         struct ide_atapi_pc *pc;
 581         ide_hwif_t *hwif = drive->hwif;
 582         ide_expiry_t *expiry = NULL;
 583         struct request *rq = hwif->rq;
 584         unsigned int timeout;
 585         u16 bcount;
 586         u8 valid_tf;
 587         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
 588
 589         if (dev_is_idecd(drive)) {
 590                 valid_tf = IDE_VALID_NSECT | IDE_VALID_LBAL;
 591                 bcount = ide_cd_get_xferlen(rq);
 592                 expiry = ide_cd_expiry;
 593                 timeout = ATAPI_WAIT_PC;
 594
 595                 if (drive->dma)
 596                         drive->dma = !ide_dma_prepare(drive, cmd);
 597         } else {
 598                 pc = drive->pc;
 599
 600                 /* We haven't transferred any data yet */
 601                 pc->xferred = 0;
 602                 pc->cur_pos = pc->buf;
 603
 604                 valid_tf = IDE_VALID_DEVICE;
 605                 bcount = ((drive->media == ide_tape) ?
 606                                 pc->req_xfer :
 607                                 min(pc->req_xfer, 63 * 1024));
 608
 609                 if (pc->flags & PC_FLAG_DMA_ERROR) {
 610                         pc->flags &= ~PC_FLAG_DMA_ERROR;
 611                         ide_dma_off(drive);
 612                 }
 613
 614                 if (pc->flags & PC_FLAG_DMA_OK)
 615                         drive->dma = !ide_dma_prepare(drive, cmd);
 616
 617                 if (!drive->dma)
 618                         pc->flags &= ~PC_FLAG_DMA_OK;
 619
 620                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
 621                                                        : WAIT_TAPE_CMD;
 622         }
 623
 624         ide_init_packet_cmd(cmd, valid_tf, bcount, drive->dma);
 625
 626         (void)do_rw_taskfile(drive, cmd);
 627
 628         if (drq_int) {
 629                 if (drive->dma)
 630                         drive->waiting_for_dma = 0;
 631                 hwif->expiry = expiry;
 632         }
 633
 634         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
 635
 636         return drq_int ? ide_started : ide_transfer_pc(drive);
 637 }
 638 EXPORT_SYMBOL_GPL(ide_issue_pc);