Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...
[kernel.git] / 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  * Add a special packet command request to the tail of the request queue,
84  * and wait for it to be serviced.
85  */
86 int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,
87                       struct ide_atapi_pc *pc)
88 {
89         struct request *rq;
90         int error;
91
92         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
93         rq->cmd_type = REQ_TYPE_SPECIAL;
94         rq->special = (char *)pc;
95
96         if (pc->req_xfer) {
97                 error = blk_rq_map_kern(drive->queue, rq, pc->buf, pc->req_xfer,
98                                         GFP_NOIO);
99                 if (error)
100                         goto put_req;
101         }
102
103         memcpy(rq->cmd, pc->c, 12);
104         if (drive->media == ide_tape)
105                 rq->cmd[13] = REQ_IDETAPE_PC1;
106         error = blk_execute_rq(drive->queue, disk, rq, 0);
107 put_req:
108         blk_put_request(rq);
109         return error;
110 }
111 EXPORT_SYMBOL_GPL(ide_queue_pc_tail);
112
113 int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
114 {
115         struct ide_atapi_pc pc;
116
117         ide_init_pc(&pc);
118         pc.c[0] = TEST_UNIT_READY;
119
120         return ide_queue_pc_tail(drive, disk, &pc);
121 }
122 EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);
123
124 int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
125 {
126         struct ide_atapi_pc pc;
127
128         ide_init_pc(&pc);
129         pc.c[0] = START_STOP;
130         pc.c[4] = start;
131
132         if (drive->media == ide_tape)
133                 pc.flags |= PC_FLAG_WAIT_FOR_DSC;
134
135         return ide_queue_pc_tail(drive, disk, &pc);
136 }
137 EXPORT_SYMBOL_GPL(ide_do_start_stop);
138
139 int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
140 {
141         struct ide_atapi_pc pc;
142
143         if ((drive->dev_flags & IDE_DFLAG_DOORLOCKING) == 0)
144                 return 0;
145
146         ide_init_pc(&pc);
147         pc.c[0] = ALLOW_MEDIUM_REMOVAL;
148         pc.c[4] = on;
149
150         return ide_queue_pc_tail(drive, disk, &pc);
151 }
152 EXPORT_SYMBOL_GPL(ide_set_media_lock);
153
154 void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
155 {
156         ide_init_pc(pc);
157         pc->c[0] = REQUEST_SENSE;
158         if (drive->media == ide_floppy) {
159                 pc->c[4] = 255;
160                 pc->req_xfer = 18;
161         } else {
162                 pc->c[4] = 20;
163                 pc->req_xfer = 20;
164         }
165 }
166 EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);
167
168 void ide_prep_sense(ide_drive_t *drive, struct request *rq)
169 {
170         struct request_sense *sense = &drive->sense_data;
171         struct request *sense_rq = &drive->sense_rq;
172         unsigned int cmd_len, sense_len;
173         int err;
174
175         debug_log("%s: enter\n", __func__);
176
177         switch (drive->media) {
178         case ide_floppy:
179                 cmd_len = 255;
180                 sense_len = 18;
181                 break;
182         case ide_tape:
183                 cmd_len = 20;
184                 sense_len = 20;
185                 break;
186         default:
187                 cmd_len = 18;
188                 sense_len = 18;
189         }
190
191         BUG_ON(sense_len > sizeof(*sense));
192
193         if (blk_sense_request(rq) || drive->sense_rq_armed)
194                 return;
195
196         memset(sense, 0, sizeof(*sense));
197
198         blk_rq_init(rq->q, sense_rq);
199
200         err = blk_rq_map_kern(drive->queue, sense_rq, sense, sense_len,
201                               GFP_NOIO);
202         if (unlikely(err)) {
203                 if (printk_ratelimit())
204                         printk(KERN_WARNING "%s: failed to map sense buffer\n",
205                                drive->name);
206                 return;
207         }
208
209         sense_rq->rq_disk = rq->rq_disk;
210         sense_rq->cmd[0] = GPCMD_REQUEST_SENSE;
211         sense_rq->cmd[4] = cmd_len;
212         sense_rq->cmd_type = REQ_TYPE_SENSE;
213         sense_rq->cmd_flags |= REQ_PREEMPT;
214
215         if (drive->media == ide_tape)
216                 sense_rq->cmd[13] = REQ_IDETAPE_PC1;
217
218         drive->sense_rq_armed = true;
219 }
220 EXPORT_SYMBOL_GPL(ide_prep_sense);
221
222 int ide_queue_sense_rq(ide_drive_t *drive, void *special)
223 {
224         /* deferred failure from ide_prep_sense() */
225         if (!drive->sense_rq_armed) {
226                 printk(KERN_WARNING "%s: failed queue sense request\n",
227                        drive->name);
228                 return -ENOMEM;
229         }
230
231         drive->sense_rq.special = special;
232         drive->sense_rq_armed = false;
233
234         drive->hwif->rq = NULL;
235
236         elv_add_request(drive->queue, &drive->sense_rq,
237                         ELEVATOR_INSERT_FRONT, 0);
238         return 0;
239 }
240 EXPORT_SYMBOL_GPL(ide_queue_sense_rq);
241
242 /*
243  * Called when an error was detected during the last packet command.
244  * We queue a request sense packet command at the head of the request
245  * queue.
246  */
247 void ide_retry_pc(ide_drive_t *drive)
248 {
249         struct request *failed_rq = drive->hwif->rq;
250         struct request *sense_rq = &drive->sense_rq;
251         struct ide_atapi_pc *pc = &drive->request_sense_pc;
252
253         (void)ide_read_error(drive);
254
255         /* init pc from sense_rq */
256         ide_init_pc(pc);
257         memcpy(pc->c, sense_rq->cmd, 12);
258         pc->buf = bio_data(sense_rq->bio);      /* pointer to mapped address */
259         pc->req_xfer = blk_rq_bytes(sense_rq);
260
261         if (drive->media == ide_tape)
262                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
263
264         /*
265          * Push back the failed request and put request sense on top
266          * of it.  The failed command will be retried after sense data
267          * is acquired.
268          */
269         blk_requeue_request(failed_rq->q, failed_rq);
270         drive->hwif->rq = NULL;
271         if (ide_queue_sense_rq(drive, pc)) {
272                 blk_start_request(failed_rq);
273                 ide_complete_rq(drive, -EIO, blk_rq_bytes(failed_rq));
274         }
275 }
276 EXPORT_SYMBOL_GPL(ide_retry_pc);
277
278 int ide_cd_expiry(ide_drive_t *drive)
279 {
280         struct request *rq = drive->hwif->rq;
281         unsigned long wait = 0;
282
283         debug_log("%s: rq->cmd[0]: 0x%x\n", __func__, rq->cmd[0]);
284
285         /*
286          * Some commands are *slow* and normally take a long time to complete.
287          * Usually we can use the ATAPI "disconnect" to bypass this, but not all
288          * commands/drives support that. Let ide_timer_expiry keep polling us
289          * for these.
290          */
291         switch (rq->cmd[0]) {
292         case GPCMD_BLANK:
293         case GPCMD_FORMAT_UNIT:
294         case GPCMD_RESERVE_RZONE_TRACK:
295         case GPCMD_CLOSE_TRACK:
296         case GPCMD_FLUSH_CACHE:
297                 wait = ATAPI_WAIT_PC;
298                 break;
299         default:
300                 if (!(rq->cmd_flags & REQ_QUIET))
301                         printk(KERN_INFO "cmd 0x%x timed out\n",
302                                          rq->cmd[0]);
303                 wait = 0;
304                 break;
305         }
306         return wait;
307 }
308 EXPORT_SYMBOL_GPL(ide_cd_expiry);
309
310 int ide_cd_get_xferlen(struct request *rq)
311 {
312         if (blk_fs_request(rq))
313                 return 32768;
314         else if (blk_sense_request(rq) || blk_pc_request(rq) ||
315                          rq->cmd_type == REQ_TYPE_ATA_PC)
316                 return blk_rq_bytes(rq);
317         else
318                 return 0;
319 }
320 EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);
321
322 void ide_read_bcount_and_ireason(ide_drive_t *drive, u16 *bcount, u8 *ireason)
323 {
324         struct ide_taskfile tf;
325
326         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT |
327                                      IDE_VALID_LBAM | IDE_VALID_LBAH);
328
329         *bcount = (tf.lbah << 8) | tf.lbam;
330         *ireason = tf.nsect & 3;
331 }
332 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
333
334 /*
335  * This is the usual interrupt handler which will be called during a packet
336  * command.  We will transfer some of the data (as requested by the drive)
337  * and will re-point interrupt handler to us.
338  */
339 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
340 {
341         struct ide_atapi_pc *pc = drive->pc;
342         ide_hwif_t *hwif = drive->hwif;
343         struct ide_cmd *cmd = &hwif->cmd;
344         struct request *rq = hwif->rq;
345         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
346         unsigned int timeout, done;
347         u16 bcount;
348         u8 stat, ireason, dsc = 0;
349         u8 write = !!(pc->flags & PC_FLAG_WRITING);
350
351         debug_log("Enter %s - interrupt handler\n", __func__);
352
353         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
354                                                : WAIT_TAPE_CMD;
355
356         /* Clear the interrupt */
357         stat = tp_ops->read_status(hwif);
358
359         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
360                 int rc;
361
362                 drive->waiting_for_dma = 0;
363                 rc = hwif->dma_ops->dma_end(drive);
364                 ide_dma_unmap_sg(drive, cmd);
365
366                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
367                         if (drive->media == ide_floppy)
368                                 printk(KERN_ERR "%s: DMA %s error\n",
369                                         drive->name, rq_data_dir(pc->rq)
370                                                      ? "write" : "read");
371                         pc->flags |= PC_FLAG_DMA_ERROR;
372                 } else
373                         pc->xferred = pc->req_xfer;
374                 debug_log("%s: DMA finished\n", drive->name);
375         }
376
377         /* No more interrupts */
378         if ((stat & ATA_DRQ) == 0) {
379                 int uptodate, error;
380
381                 debug_log("Packet command completed, %d bytes transferred\n",
382                           pc->xferred);
383
384                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
385
386                 local_irq_enable_in_hardirq();
387
388                 if (drive->media == ide_tape &&
389                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
390                         stat &= ~ATA_ERR;
391
392                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
393                         /* Error detected */
394                         debug_log("%s: I/O error\n", drive->name);
395
396                         if (drive->media != ide_tape)
397                                 pc->rq->errors++;
398
399                         if (rq->cmd[0] == REQUEST_SENSE) {
400                                 printk(KERN_ERR "%s: I/O error in request sense"
401                                                 " command\n", drive->name);
402                                 return ide_do_reset(drive);
403                         }
404
405                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
406
407                         /* Retry operation */
408                         ide_retry_pc(drive);
409
410                         /* queued, but not started */
411                         return ide_stopped;
412                 }
413                 pc->error = 0;
414
415                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
416                         dsc = 1;
417
418                 /*
419                  * ->pc_callback() might change rq->data_len for
420                  * residual count, cache total length.
421                  */
422                 done = blk_rq_bytes(rq);
423
424                 /* Command finished - Call the callback function */
425                 uptodate = drive->pc_callback(drive, dsc);
426
427                 if (uptodate == 0)
428                         drive->failed_pc = NULL;
429
430                 if (blk_special_request(rq)) {
431                         rq->errors = 0;
432                         error = 0;
433                 } else {
434
435                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
436                                 if (rq->errors == 0)
437                                         rq->errors = -EIO;
438                         }
439
440                         error = uptodate ? 0 : -EIO;
441                 }
442
443                 ide_complete_rq(drive, error, blk_rq_bytes(rq));
444                 return ide_stopped;
445         }
446
447         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
448                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
449                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
450                                 "in DMA mode\n", drive->name);
451                 ide_dma_off(drive);
452                 return ide_do_reset(drive);
453         }
454
455         /* Get the number of bytes to transfer on this interrupt. */
456         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
457
458         if (ireason & ATAPI_COD) {
459                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
460                 return ide_do_reset(drive);
461         }
462
463         if (((ireason & ATAPI_IO) == ATAPI_IO) == write) {
464                 /* Hopefully, we will never get here */
465                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
466                                 "to %s!\n", drive->name,
467                                 (ireason & ATAPI_IO) ? "Write" : "Read",
468                                 (ireason & ATAPI_IO) ? "Read" : "Write");
469                 return ide_do_reset(drive);
470         }
471
472         done = min_t(unsigned int, bcount, cmd->nleft);
473         ide_pio_bytes(drive, cmd, write, done);
474
475         /* Update transferred byte count */
476         pc->xferred += done;
477
478         bcount -= done;
479
480         if (bcount)
481                 ide_pad_transfer(drive, write, bcount);
482
483         debug_log("[cmd %x] transferred %d bytes, padded %d bytes\n",
484                   rq->cmd[0], done, bcount);
485
486         /* And set the interrupt handler again */
487         ide_set_handler(drive, ide_pc_intr, timeout);
488         return ide_started;
489 }
490
491 static void ide_init_packet_cmd(struct ide_cmd *cmd, u8 valid_tf,
492                                 u16 bcount, u8 dma)
493 {
494         cmd->protocol = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
495         cmd->valid.out.tf = IDE_VALID_LBAH | IDE_VALID_LBAM |
496                             IDE_VALID_FEATURE | valid_tf;
497         cmd->tf.command = ATA_CMD_PACKET;
498         cmd->tf.feature = dma;          /* Use PIO/DMA */
499         cmd->tf.lbam    = bcount & 0xff;
500         cmd->tf.lbah    = (bcount >> 8) & 0xff;
501 }
502
503 static u8 ide_read_ireason(ide_drive_t *drive)
504 {
505         struct ide_taskfile tf;
506
507         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT);
508
509         return tf.nsect & 3;
510 }
511
512 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
513 {
514         int retries = 100;
515
516         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
517                 (ireason & ATAPI_IO))) {
518                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
519                                 "a packet command, retrying\n", drive->name);
520                 udelay(100);
521                 ireason = ide_read_ireason(drive);
522                 if (retries == 0) {
523                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
524                                         "a packet command, ignoring\n",
525                                         drive->name);
526                         ireason |= ATAPI_COD;
527                         ireason &= ~ATAPI_IO;
528                 }
529         }
530
531         return ireason;
532 }
533
534 static int ide_delayed_transfer_pc(ide_drive_t *drive)
535 {
536         /* Send the actual packet */
537         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
538
539         /* Timeout for the packet command */
540         return WAIT_FLOPPY_CMD;
541 }
542
543 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
544 {
545         struct ide_atapi_pc *uninitialized_var(pc);
546         ide_hwif_t *hwif = drive->hwif;
547         struct request *rq = hwif->rq;
548         ide_expiry_t *expiry;
549         unsigned int timeout;
550         int cmd_len;
551         ide_startstop_t startstop;
552         u8 ireason;
553
554         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
555                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
556                                 "DRQ isn't asserted\n", drive->name);
557                 return startstop;
558         }
559
560         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
561                 if (drive->dma)
562                         drive->waiting_for_dma = 1;
563         }
564
565         if (dev_is_idecd(drive)) {
566                 /* ATAPI commands get padded out to 12 bytes minimum */
567                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
568                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
569                         cmd_len = ATAPI_MIN_CDB_BYTES;
570
571                 timeout = rq->timeout;
572                 expiry  = ide_cd_expiry;
573         } else {
574                 pc = drive->pc;
575
576                 cmd_len = ATAPI_MIN_CDB_BYTES;
577
578                 /*
579                  * If necessary schedule the packet transfer to occur 'timeout'
580                  * miliseconds later in ide_delayed_transfer_pc() after the
581                  * device says it's ready for a packet.
582                  */
583                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
584                         timeout = drive->pc_delay;
585                         expiry = &ide_delayed_transfer_pc;
586                 } else {
587                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
588                                                                : WAIT_TAPE_CMD;
589                         expiry = NULL;
590                 }
591
592                 ireason = ide_read_ireason(drive);
593                 if (drive->media == ide_tape)
594                         ireason = ide_wait_ireason(drive, ireason);
595
596                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
597                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
598                                         "a packet command\n", drive->name);
599
600                         return ide_do_reset(drive);
601                 }
602         }
603
604         hwif->expiry = expiry;
605
606         /* Set the interrupt routine */
607         ide_set_handler(drive,
608                         (dev_is_idecd(drive) ? drive->irq_handler
609                                              : ide_pc_intr),
610                         timeout);
611
612         /* Send the actual packet */
613         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
614                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
615
616         /* Begin DMA, if necessary */
617         if (dev_is_idecd(drive)) {
618                 if (drive->dma)
619                         hwif->dma_ops->dma_start(drive);
620         } else {
621                 if (pc->flags & PC_FLAG_DMA_OK) {
622                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
623                         hwif->dma_ops->dma_start(drive);
624                 }
625         }
626
627         return ide_started;
628 }
629
630 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
631 {
632         struct ide_atapi_pc *pc;
633         ide_hwif_t *hwif = drive->hwif;
634         ide_expiry_t *expiry = NULL;
635         struct request *rq = hwif->rq;
636         unsigned int timeout;
637         u16 bcount;
638         u8 valid_tf;
639         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
640
641         if (dev_is_idecd(drive)) {
642                 valid_tf = IDE_VALID_NSECT | IDE_VALID_LBAL;
643                 bcount = ide_cd_get_xferlen(rq);
644                 expiry = ide_cd_expiry;
645                 timeout = ATAPI_WAIT_PC;
646
647                 if (drive->dma)
648                         drive->dma = !ide_dma_prepare(drive, cmd);
649         } else {
650                 pc = drive->pc;
651
652                 /* We haven't transferred any data yet */
653                 pc->xferred = 0;
654
655                 valid_tf = IDE_VALID_DEVICE;
656                 bcount = ((drive->media == ide_tape) ?
657                                 pc->req_xfer :
658                                 min(pc->req_xfer, 63 * 1024));
659
660                 if (pc->flags & PC_FLAG_DMA_ERROR) {
661                         pc->flags &= ~PC_FLAG_DMA_ERROR;
662                         ide_dma_off(drive);
663                 }
664
665                 if (pc->flags & PC_FLAG_DMA_OK)
666                         drive->dma = !ide_dma_prepare(drive, cmd);
667
668                 if (!drive->dma)
669                         pc->flags &= ~PC_FLAG_DMA_OK;
670
671                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
672                                                        : WAIT_TAPE_CMD;
673         }
674
675         ide_init_packet_cmd(cmd, valid_tf, bcount, drive->dma);
676
677         (void)do_rw_taskfile(drive, cmd);
678
679         if (drq_int) {
680                 if (drive->dma)
681                         drive->waiting_for_dma = 0;
682                 hwif->expiry = expiry;
683         }
684
685         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
686
687         return drq_int ? ide_started : ide_transfer_pc(drive);
688 }
689 EXPORT_SYMBOL_GPL(ide_issue_pc);