ide-cd,atapi: use bio for internal commands
[linux-2.6.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 *sense_rq = &drive->sense_rq;
250         struct ide_atapi_pc *pc = &drive->request_sense_pc;
251
252         (void)ide_read_error(drive);
253
254         /* init pc from sense_rq */
255         ide_init_pc(pc);
256         memcpy(pc->c, sense_rq->cmd, 12);
257         pc->buf = bio_data(sense_rq->bio);      /* pointer to mapped address */
258         pc->req_xfer = sense_rq->data_len;
259
260         if (drive->media == ide_tape)
261                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
262
263         if (ide_queue_sense_rq(drive, pc))
264                 ide_complete_rq(drive, -EIO, blk_rq_bytes(drive->hwif->rq));
265 }
266 EXPORT_SYMBOL_GPL(ide_retry_pc);
267
268 int ide_cd_expiry(ide_drive_t *drive)
269 {
270         struct request *rq = drive->hwif->rq;
271         unsigned long wait = 0;
272
273         debug_log("%s: rq->cmd[0]: 0x%x\n", __func__, rq->cmd[0]);
274
275         /*
276          * Some commands are *slow* and normally take a long time to complete.
277          * Usually we can use the ATAPI "disconnect" to bypass this, but not all
278          * commands/drives support that. Let ide_timer_expiry keep polling us
279          * for these.
280          */
281         switch (rq->cmd[0]) {
282         case GPCMD_BLANK:
283         case GPCMD_FORMAT_UNIT:
284         case GPCMD_RESERVE_RZONE_TRACK:
285         case GPCMD_CLOSE_TRACK:
286         case GPCMD_FLUSH_CACHE:
287                 wait = ATAPI_WAIT_PC;
288                 break;
289         default:
290                 if (!(rq->cmd_flags & REQ_QUIET))
291                         printk(KERN_INFO "cmd 0x%x timed out\n",
292                                          rq->cmd[0]);
293                 wait = 0;
294                 break;
295         }
296         return wait;
297 }
298 EXPORT_SYMBOL_GPL(ide_cd_expiry);
299
300 int ide_cd_get_xferlen(struct request *rq)
301 {
302         if (blk_fs_request(rq))
303                 return 32768;
304         else if (blk_sense_request(rq) || blk_pc_request(rq) ||
305                          rq->cmd_type == REQ_TYPE_ATA_PC)
306                 return rq->data_len;
307         else
308                 return 0;
309 }
310 EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);
311
312 void ide_read_bcount_and_ireason(ide_drive_t *drive, u16 *bcount, u8 *ireason)
313 {
314         struct ide_taskfile tf;
315
316         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT |
317                                      IDE_VALID_LBAM | IDE_VALID_LBAH);
318
319         *bcount = (tf.lbah << 8) | tf.lbam;
320         *ireason = tf.nsect & 3;
321 }
322 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
323
324 /*
325  * This is the usual interrupt handler which will be called during a packet
326  * command.  We will transfer some of the data (as requested by the drive)
327  * and will re-point interrupt handler to us.
328  */
329 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
330 {
331         struct ide_atapi_pc *pc = drive->pc;
332         ide_hwif_t *hwif = drive->hwif;
333         struct ide_cmd *cmd = &hwif->cmd;
334         struct request *rq = hwif->rq;
335         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
336         unsigned int timeout, done;
337         u16 bcount;
338         u8 stat, ireason, dsc = 0;
339         u8 write = !!(pc->flags & PC_FLAG_WRITING);
340
341         debug_log("Enter %s - interrupt handler\n", __func__);
342
343         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
344                                                : WAIT_TAPE_CMD;
345
346         /* Clear the interrupt */
347         stat = tp_ops->read_status(hwif);
348
349         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
350                 int rc;
351
352                 drive->waiting_for_dma = 0;
353                 rc = hwif->dma_ops->dma_end(drive);
354                 ide_dma_unmap_sg(drive, cmd);
355
356                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
357                         if (drive->media == ide_floppy)
358                                 printk(KERN_ERR "%s: DMA %s error\n",
359                                         drive->name, rq_data_dir(pc->rq)
360                                                      ? "write" : "read");
361                         pc->flags |= PC_FLAG_DMA_ERROR;
362                 } else {
363                         pc->xferred = pc->req_xfer;
364                         if (drive->pc_update_buffers)
365                                 drive->pc_update_buffers(drive, pc);
366                 }
367                 debug_log("%s: DMA finished\n", drive->name);
368         }
369
370         /* No more interrupts */
371         if ((stat & ATA_DRQ) == 0) {
372                 int uptodate, error;
373                 unsigned int done;
374
375                 debug_log("Packet command completed, %d bytes transferred\n",
376                           pc->xferred);
377
378                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
379
380                 local_irq_enable_in_hardirq();
381
382                 if (drive->media == ide_tape &&
383                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
384                         stat &= ~ATA_ERR;
385
386                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
387                         /* Error detected */
388                         debug_log("%s: I/O error\n", drive->name);
389
390                         if (drive->media != ide_tape)
391                                 pc->rq->errors++;
392
393                         if (rq->cmd[0] == REQUEST_SENSE) {
394                                 printk(KERN_ERR "%s: I/O error in request sense"
395                                                 " command\n", drive->name);
396                                 return ide_do_reset(drive);
397                         }
398
399                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
400
401                         /* Retry operation */
402                         ide_retry_pc(drive);
403
404                         /* queued, but not started */
405                         return ide_stopped;
406                 }
407                 pc->error = 0;
408
409                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
410                         dsc = 1;
411
412                 /* Command finished - Call the callback function */
413                 uptodate = drive->pc_callback(drive, dsc);
414
415                 if (uptodate == 0)
416                         drive->failed_pc = NULL;
417
418                 if (blk_special_request(rq)) {
419                         rq->errors = 0;
420                         done = blk_rq_bytes(rq);
421                         error = 0;
422                 } else {
423
424                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
425                                 if (rq->errors == 0)
426                                         rq->errors = -EIO;
427                         }
428
429                         if (drive->media == ide_tape && !rq->bio)
430                                 done = ide_rq_bytes(rq); /* FIXME */
431                         else
432                                 done = blk_rq_bytes(rq);
433
434                         error = uptodate ? 0 : -EIO;
435                 }
436
437                 ide_complete_rq(drive, error, done);
438                 return ide_stopped;
439         }
440
441         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
442                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
443                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
444                                 "in DMA mode\n", drive->name);
445                 ide_dma_off(drive);
446                 return ide_do_reset(drive);
447         }
448
449         /* Get the number of bytes to transfer on this interrupt. */
450         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
451
452         if (ireason & ATAPI_COD) {
453                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
454                 return ide_do_reset(drive);
455         }
456
457         if (((ireason & ATAPI_IO) == ATAPI_IO) == write) {
458                 /* Hopefully, we will never get here */
459                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
460                                 "to %s!\n", drive->name,
461                                 (ireason & ATAPI_IO) ? "Write" : "Read",
462                                 (ireason & ATAPI_IO) ? "Read" : "Write");
463                 return ide_do_reset(drive);
464         }
465
466         if (drive->media == ide_tape && pc->bh)
467                 done = drive->pc_io_buffers(drive, pc, bcount, write);
468         else {
469                 done = min_t(unsigned int, bcount, cmd->nleft);
470                 ide_pio_bytes(drive, cmd, write, done);
471         }
472
473         /* Update the current position */
474         pc->xferred += done;
475         pc->cur_pos += done;
476
477         bcount -= done;
478
479         if (bcount)
480                 ide_pad_transfer(drive, write, bcount);
481
482         debug_log("[cmd %x] transferred %d bytes, padded %d bytes\n",
483                   rq->cmd[0], done, bcount);
484
485         /* And set the interrupt handler again */
486         ide_set_handler(drive, ide_pc_intr, timeout);
487         return ide_started;
488 }
489
490 static void ide_init_packet_cmd(struct ide_cmd *cmd, u8 valid_tf,
491                                 u16 bcount, u8 dma)
492 {
493         cmd->protocol = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
494         cmd->valid.out.tf = IDE_VALID_LBAH | IDE_VALID_LBAM |
495                             IDE_VALID_FEATURE | valid_tf;
496         cmd->tf.command = ATA_CMD_PACKET;
497         cmd->tf.feature = dma;          /* Use PIO/DMA */
498         cmd->tf.lbam    = bcount & 0xff;
499         cmd->tf.lbah    = (bcount >> 8) & 0xff;
500 }
501
502 static u8 ide_read_ireason(ide_drive_t *drive)
503 {
504         struct ide_taskfile tf;
505
506         drive->hwif->tp_ops->tf_read(drive, &tf, IDE_VALID_NSECT);
507
508         return tf.nsect & 3;
509 }
510
511 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
512 {
513         int retries = 100;
514
515         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
516                 (ireason & ATAPI_IO))) {
517                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
518                                 "a packet command, retrying\n", drive->name);
519                 udelay(100);
520                 ireason = ide_read_ireason(drive);
521                 if (retries == 0) {
522                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
523                                         "a packet command, ignoring\n",
524                                         drive->name);
525                         ireason |= ATAPI_COD;
526                         ireason &= ~ATAPI_IO;
527                 }
528         }
529
530         return ireason;
531 }
532
533 static int ide_delayed_transfer_pc(ide_drive_t *drive)
534 {
535         /* Send the actual packet */
536         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
537
538         /* Timeout for the packet command */
539         return WAIT_FLOPPY_CMD;
540 }
541
542 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
543 {
544         struct ide_atapi_pc *uninitialized_var(pc);
545         ide_hwif_t *hwif = drive->hwif;
546         struct request *rq = hwif->rq;
547         ide_expiry_t *expiry;
548         unsigned int timeout;
549         int cmd_len;
550         ide_startstop_t startstop;
551         u8 ireason;
552
553         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
554                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
555                                 "DRQ isn't asserted\n", drive->name);
556                 return startstop;
557         }
558
559         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
560                 if (drive->dma)
561                         drive->waiting_for_dma = 1;
562         }
563
564         if (dev_is_idecd(drive)) {
565                 /* ATAPI commands get padded out to 12 bytes minimum */
566                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
567                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
568                         cmd_len = ATAPI_MIN_CDB_BYTES;
569
570                 timeout = rq->timeout;
571                 expiry  = ide_cd_expiry;
572         } else {
573                 pc = drive->pc;
574
575                 cmd_len = ATAPI_MIN_CDB_BYTES;
576
577                 /*
578                  * If necessary schedule the packet transfer to occur 'timeout'
579                  * miliseconds later in ide_delayed_transfer_pc() after the
580                  * device says it's ready for a packet.
581                  */
582                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
583                         timeout = drive->pc_delay;
584                         expiry = &ide_delayed_transfer_pc;
585                 } else {
586                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
587                                                                : WAIT_TAPE_CMD;
588                         expiry = NULL;
589                 }
590
591                 ireason = ide_read_ireason(drive);
592                 if (drive->media == ide_tape)
593                         ireason = ide_wait_ireason(drive, ireason);
594
595                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
596                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
597                                         "a packet command\n", drive->name);
598
599                         return ide_do_reset(drive);
600                 }
601         }
602
603         hwif->expiry = expiry;
604
605         /* Set the interrupt routine */
606         ide_set_handler(drive,
607                         (dev_is_idecd(drive) ? drive->irq_handler
608                                              : ide_pc_intr),
609                         timeout);
610
611         /* Send the actual packet */
612         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
613                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
614
615         /* Begin DMA, if necessary */
616         if (dev_is_idecd(drive)) {
617                 if (drive->dma)
618                         hwif->dma_ops->dma_start(drive);
619         } else {
620                 if (pc->flags & PC_FLAG_DMA_OK) {
621                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
622                         hwif->dma_ops->dma_start(drive);
623                 }
624         }
625
626         return ide_started;
627 }
628
629 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
630 {
631         struct ide_atapi_pc *pc;
632         ide_hwif_t *hwif = drive->hwif;
633         ide_expiry_t *expiry = NULL;
634         struct request *rq = hwif->rq;
635         unsigned int timeout;
636         u16 bcount;
637         u8 valid_tf;
638         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
639
640         if (dev_is_idecd(drive)) {
641                 valid_tf = IDE_VALID_NSECT | IDE_VALID_LBAL;
642                 bcount = ide_cd_get_xferlen(rq);
643                 expiry = ide_cd_expiry;
644                 timeout = ATAPI_WAIT_PC;
645
646                 if (drive->dma)
647                         drive->dma = !ide_dma_prepare(drive, cmd);
648         } else {
649                 pc = drive->pc;
650
651                 /* We haven't transferred any data yet */
652                 pc->xferred = 0;
653                 pc->cur_pos = pc->buf;
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);