ide-{floppy,tape}: fix padding for PIO transfers
[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 /* PIO data transfer routine using the scatter gather table. */
75 int ide_io_buffers(ide_drive_t *drive, struct ide_atapi_pc *pc,
76                     unsigned int bcount, int write)
77 {
78         ide_hwif_t *hwif = drive->hwif;
79         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
80         xfer_func_t *xf = write ? tp_ops->output_data : tp_ops->input_data;
81         struct scatterlist *sg = pc->sg;
82         char *buf;
83         int count, done = 0;
84
85         while (bcount) {
86                 count = min(sg->length - pc->b_count, bcount);
87
88                 if (PageHighMem(sg_page(sg))) {
89                         unsigned long flags;
90
91                         local_irq_save(flags);
92                         buf = kmap_atomic(sg_page(sg), KM_IRQ0) + sg->offset;
93                         xf(drive, NULL, buf + pc->b_count, count);
94                         kunmap_atomic(buf - sg->offset, KM_IRQ0);
95                         local_irq_restore(flags);
96                 } else {
97                         buf = sg_virt(sg);
98                         xf(drive, NULL, buf + pc->b_count, count);
99                 }
100
101                 bcount -= count;
102                 pc->b_count += count;
103                 done += count;
104
105                 if (pc->b_count == sg->length) {
106                         if (!--pc->sg_cnt)
107                                 break;
108                         pc->sg = sg = sg_next(sg);
109                         pc->b_count = 0;
110                 }
111         }
112
113         return done;
114 }
115 EXPORT_SYMBOL_GPL(ide_io_buffers);
116
117 void ide_init_pc(struct ide_atapi_pc *pc)
118 {
119         memset(pc, 0, sizeof(*pc));
120         pc->buf = pc->pc_buf;
121         pc->buf_size = IDE_PC_BUFFER_SIZE;
122 }
123 EXPORT_SYMBOL_GPL(ide_init_pc);
124
125 /*
126  * Generate a new packet command request in front of the request queue, before
127  * the current request, so that it will be processed immediately, on the next
128  * pass through the driver.
129  */
130 static void ide_queue_pc_head(ide_drive_t *drive, struct gendisk *disk,
131                               struct ide_atapi_pc *pc, struct request *rq)
132 {
133         blk_rq_init(NULL, rq);
134         rq->cmd_type = REQ_TYPE_SPECIAL;
135         rq->cmd_flags |= REQ_PREEMPT;
136         rq->buffer = (char *)pc;
137         rq->rq_disk = disk;
138
139         if (pc->req_xfer) {
140                 rq->data = pc->buf;
141                 rq->data_len = pc->req_xfer;
142         }
143
144         memcpy(rq->cmd, pc->c, 12);
145         if (drive->media == ide_tape)
146                 rq->cmd[13] = REQ_IDETAPE_PC1;
147
148         drive->hwif->rq = NULL;
149
150         elv_add_request(drive->queue, rq, ELEVATOR_INSERT_FRONT, 0);
151 }
152
153 /*
154  * Add a special packet command request to the tail of the request queue,
155  * and wait for it to be serviced.
156  */
157 int ide_queue_pc_tail(ide_drive_t *drive, struct gendisk *disk,
158                       struct ide_atapi_pc *pc)
159 {
160         struct request *rq;
161         int error;
162
163         rq = blk_get_request(drive->queue, READ, __GFP_WAIT);
164         rq->cmd_type = REQ_TYPE_SPECIAL;
165         rq->buffer = (char *)pc;
166
167         if (pc->req_xfer) {
168                 rq->data = pc->buf;
169                 rq->data_len = pc->req_xfer;
170         }
171
172         memcpy(rq->cmd, pc->c, 12);
173         if (drive->media == ide_tape)
174                 rq->cmd[13] = REQ_IDETAPE_PC1;
175         error = blk_execute_rq(drive->queue, disk, rq, 0);
176         blk_put_request(rq);
177
178         return error;
179 }
180 EXPORT_SYMBOL_GPL(ide_queue_pc_tail);
181
182 int ide_do_test_unit_ready(ide_drive_t *drive, struct gendisk *disk)
183 {
184         struct ide_atapi_pc pc;
185
186         ide_init_pc(&pc);
187         pc.c[0] = TEST_UNIT_READY;
188
189         return ide_queue_pc_tail(drive, disk, &pc);
190 }
191 EXPORT_SYMBOL_GPL(ide_do_test_unit_ready);
192
193 int ide_do_start_stop(ide_drive_t *drive, struct gendisk *disk, int start)
194 {
195         struct ide_atapi_pc pc;
196
197         ide_init_pc(&pc);
198         pc.c[0] = START_STOP;
199         pc.c[4] = start;
200
201         if (drive->media == ide_tape)
202                 pc.flags |= PC_FLAG_WAIT_FOR_DSC;
203
204         return ide_queue_pc_tail(drive, disk, &pc);
205 }
206 EXPORT_SYMBOL_GPL(ide_do_start_stop);
207
208 int ide_set_media_lock(ide_drive_t *drive, struct gendisk *disk, int on)
209 {
210         struct ide_atapi_pc pc;
211
212         if ((drive->dev_flags & IDE_DFLAG_DOORLOCKING) == 0)
213                 return 0;
214
215         ide_init_pc(&pc);
216         pc.c[0] = ALLOW_MEDIUM_REMOVAL;
217         pc.c[4] = on;
218
219         return ide_queue_pc_tail(drive, disk, &pc);
220 }
221 EXPORT_SYMBOL_GPL(ide_set_media_lock);
222
223 void ide_create_request_sense_cmd(ide_drive_t *drive, struct ide_atapi_pc *pc)
224 {
225         ide_init_pc(pc);
226         pc->c[0] = REQUEST_SENSE;
227         if (drive->media == ide_floppy) {
228                 pc->c[4] = 255;
229                 pc->req_xfer = 18;
230         } else {
231                 pc->c[4] = 20;
232                 pc->req_xfer = 20;
233         }
234 }
235 EXPORT_SYMBOL_GPL(ide_create_request_sense_cmd);
236
237 /*
238  * Called when an error was detected during the last packet command.
239  * We queue a request sense packet command in the head of the request list.
240  */
241 void ide_retry_pc(ide_drive_t *drive, struct gendisk *disk)
242 {
243         struct request *rq = &drive->request_sense_rq;
244         struct ide_atapi_pc *pc = &drive->request_sense_pc;
245
246         (void)ide_read_error(drive);
247         ide_create_request_sense_cmd(drive, pc);
248         if (drive->media == ide_tape)
249                 set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
250         ide_queue_pc_head(drive, disk, pc, rq);
251 }
252 EXPORT_SYMBOL_GPL(ide_retry_pc);
253
254 int ide_cd_expiry(ide_drive_t *drive)
255 {
256         struct request *rq = drive->hwif->rq;
257         unsigned long wait = 0;
258
259         debug_log("%s: rq->cmd[0]: 0x%x\n", __func__, rq->cmd[0]);
260
261         /*
262          * Some commands are *slow* and normally take a long time to complete.
263          * Usually we can use the ATAPI "disconnect" to bypass this, but not all
264          * commands/drives support that. Let ide_timer_expiry keep polling us
265          * for these.
266          */
267         switch (rq->cmd[0]) {
268         case GPCMD_BLANK:
269         case GPCMD_FORMAT_UNIT:
270         case GPCMD_RESERVE_RZONE_TRACK:
271         case GPCMD_CLOSE_TRACK:
272         case GPCMD_FLUSH_CACHE:
273                 wait = ATAPI_WAIT_PC;
274                 break;
275         default:
276                 if (!(rq->cmd_flags & REQ_QUIET))
277                         printk(KERN_INFO "cmd 0x%x timed out\n",
278                                          rq->cmd[0]);
279                 wait = 0;
280                 break;
281         }
282         return wait;
283 }
284 EXPORT_SYMBOL_GPL(ide_cd_expiry);
285
286 int ide_cd_get_xferlen(struct request *rq)
287 {
288         if (blk_fs_request(rq))
289                 return 32768;
290         else if (blk_sense_request(rq) || blk_pc_request(rq) ||
291                          rq->cmd_type == REQ_TYPE_ATA_PC)
292                 return rq->data_len;
293         else
294                 return 0;
295 }
296 EXPORT_SYMBOL_GPL(ide_cd_get_xferlen);
297
298 void ide_read_bcount_and_ireason(ide_drive_t *drive, u16 *bcount, u8 *ireason)
299 {
300         struct ide_cmd cmd;
301
302         memset(&cmd, 0, sizeof(cmd));
303         cmd.tf_flags = IDE_TFLAG_IN_LBAH | IDE_TFLAG_IN_LBAM |
304                        IDE_TFLAG_IN_NSECT;
305
306         drive->hwif->tp_ops->tf_read(drive, &cmd);
307
308         *bcount = (cmd.tf.lbah << 8) | cmd.tf.lbam;
309         *ireason = cmd.tf.nsect & 3;
310 }
311 EXPORT_SYMBOL_GPL(ide_read_bcount_and_ireason);
312
313 /*
314  * This is the usual interrupt handler which will be called during a packet
315  * command.  We will transfer some of the data (as requested by the drive)
316  * and will re-point interrupt handler to us.
317  */
318 static ide_startstop_t ide_pc_intr(ide_drive_t *drive)
319 {
320         struct ide_atapi_pc *pc = drive->pc;
321         ide_hwif_t *hwif = drive->hwif;
322         struct ide_cmd *cmd = &hwif->cmd;
323         struct request *rq = hwif->rq;
324         const struct ide_tp_ops *tp_ops = hwif->tp_ops;
325         xfer_func_t *xferfunc;
326         unsigned int timeout, done;
327         u16 bcount;
328         u8 stat, ireason, dsc = 0;
329         u8 write = !!(pc->flags & PC_FLAG_WRITING);
330
331         debug_log("Enter %s - interrupt handler\n", __func__);
332
333         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
334                                                : WAIT_TAPE_CMD;
335
336         /* Clear the interrupt */
337         stat = tp_ops->read_status(hwif);
338
339         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
340                 int rc;
341
342                 drive->waiting_for_dma = 0;
343                 rc = hwif->dma_ops->dma_end(drive);
344                 ide_dma_unmap_sg(drive, cmd);
345
346                 if (rc || (drive->media == ide_tape && (stat & ATA_ERR))) {
347                         if (drive->media == ide_floppy)
348                                 printk(KERN_ERR "%s: DMA %s error\n",
349                                         drive->name, rq_data_dir(pc->rq)
350                                                      ? "write" : "read");
351                         pc->flags |= PC_FLAG_DMA_ERROR;
352                 } else {
353                         pc->xferred = pc->req_xfer;
354                         if (drive->pc_update_buffers)
355                                 drive->pc_update_buffers(drive, pc);
356                 }
357                 debug_log("%s: DMA finished\n", drive->name);
358         }
359
360         /* No more interrupts */
361         if ((stat & ATA_DRQ) == 0) {
362                 int uptodate;
363
364                 debug_log("Packet command completed, %d bytes transferred\n",
365                           pc->xferred);
366
367                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
368
369                 local_irq_enable_in_hardirq();
370
371                 if (drive->media == ide_tape &&
372                     (stat & ATA_ERR) && rq->cmd[0] == REQUEST_SENSE)
373                         stat &= ~ATA_ERR;
374
375                 if ((stat & ATA_ERR) || (pc->flags & PC_FLAG_DMA_ERROR)) {
376                         /* Error detected */
377                         debug_log("%s: I/O error\n", drive->name);
378
379                         if (drive->media != ide_tape)
380                                 pc->rq->errors++;
381
382                         if (rq->cmd[0] == REQUEST_SENSE) {
383                                 printk(KERN_ERR "%s: I/O error in request sense"
384                                                 " command\n", drive->name);
385                                 return ide_do_reset(drive);
386                         }
387
388                         debug_log("[cmd %x]: check condition\n", rq->cmd[0]);
389
390                         /* Retry operation */
391                         ide_retry_pc(drive, rq->rq_disk);
392
393                         /* queued, but not started */
394                         return ide_stopped;
395                 }
396                 pc->error = 0;
397
398                 if ((pc->flags & PC_FLAG_WAIT_FOR_DSC) && (stat & ATA_DSC) == 0)
399                         dsc = 1;
400
401                 /* Command finished - Call the callback function */
402                 uptodate = drive->pc_callback(drive, dsc);
403
404                 if (uptodate == 0)
405                         drive->failed_pc = NULL;
406
407                 if (blk_special_request(rq)) {
408                         rq->errors = 0;
409                         ide_complete_rq(drive, 0, blk_rq_bytes(rq));
410                 } else {
411                         if (blk_fs_request(rq) == 0 && uptodate <= 0) {
412                                 if (rq->errors == 0)
413                                         rq->errors = -EIO;
414                         }
415                         ide_complete_rq(drive, uptodate ? 0 : -EIO,
416                                         ide_rq_bytes(rq));
417                 }
418
419                 return ide_stopped;
420         }
421
422         if (pc->flags & PC_FLAG_DMA_IN_PROGRESS) {
423                 pc->flags &= ~PC_FLAG_DMA_IN_PROGRESS;
424                 printk(KERN_ERR "%s: The device wants to issue more interrupts "
425                                 "in DMA mode\n", drive->name);
426                 ide_dma_off(drive);
427                 return ide_do_reset(drive);
428         }
429
430         /* Get the number of bytes to transfer on this interrupt. */
431         ide_read_bcount_and_ireason(drive, &bcount, &ireason);
432
433         if (ireason & ATAPI_COD) {
434                 printk(KERN_ERR "%s: CoD != 0 in %s\n", drive->name, __func__);
435                 return ide_do_reset(drive);
436         }
437
438         if (((ireason & ATAPI_IO) == ATAPI_IO) == write) {
439                 /* Hopefully, we will never get here */
440                 printk(KERN_ERR "%s: We wanted to %s, but the device wants us "
441                                 "to %s!\n", drive->name,
442                                 (ireason & ATAPI_IO) ? "Write" : "Read",
443                                 (ireason & ATAPI_IO) ? "Read" : "Write");
444                 return ide_do_reset(drive);
445         }
446
447         xferfunc = write ? tp_ops->output_data : tp_ops->input_data;
448
449         if ((drive->media == ide_floppy && !pc->buf) ||
450             (drive->media == ide_tape && pc->bh)) {
451                 done = drive->pc_io_buffers(drive, pc, bcount, write);
452
453                 /* FIXME: don't do partial completions */
454                 if (drive->media == ide_floppy)
455                         ide_complete_rq(drive, 0,
456                                         done ? done : ide_rq_bytes(rq));
457         } else {
458                 done = min_t(unsigned int, bcount, pc->req_xfer - pc->xferred);
459                 xferfunc(drive, NULL, pc->cur_pos, done);
460         }
461
462         /* Update the current position */
463         pc->xferred += done;
464         pc->cur_pos += done;
465
466         bcount -= done;
467
468         if (bcount)
469                 ide_pad_transfer(drive, write, bcount);
470
471         debug_log("[cmd %x] transferred %d bytes, padded %d bytes\n",
472                   rq->cmd[0], done, bcount);
473
474         /* And set the interrupt handler again */
475         ide_set_handler(drive, ide_pc_intr, timeout);
476         return ide_started;
477 }
478
479 static void ide_init_packet_cmd(struct ide_cmd *cmd, u32 tf_flags,
480                                 u16 bcount, u8 dma)
481 {
482         cmd->protocol  = dma ? ATAPI_PROT_DMA : ATAPI_PROT_PIO;
483         cmd->tf_flags |= IDE_TFLAG_OUT_LBAH | IDE_TFLAG_OUT_LBAM |
484                          IDE_TFLAG_OUT_FEATURE | tf_flags;
485         cmd->tf.command = ATA_CMD_PACKET;
486         cmd->tf.feature = dma;          /* Use PIO/DMA */
487         cmd->tf.lbam    = bcount & 0xff;
488         cmd->tf.lbah    = (bcount >> 8) & 0xff;
489 }
490
491 static u8 ide_read_ireason(ide_drive_t *drive)
492 {
493         struct ide_cmd cmd;
494
495         memset(&cmd, 0, sizeof(cmd));
496         cmd.tf_flags = IDE_TFLAG_IN_NSECT;
497
498         drive->hwif->tp_ops->tf_read(drive, &cmd);
499
500         return cmd.tf.nsect & 3;
501 }
502
503 static u8 ide_wait_ireason(ide_drive_t *drive, u8 ireason)
504 {
505         int retries = 100;
506
507         while (retries-- && ((ireason & ATAPI_COD) == 0 ||
508                 (ireason & ATAPI_IO))) {
509                 printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
510                                 "a packet command, retrying\n", drive->name);
511                 udelay(100);
512                 ireason = ide_read_ireason(drive);
513                 if (retries == 0) {
514                         printk(KERN_ERR "%s: (IO,CoD != (0,1) while issuing "
515                                         "a packet command, ignoring\n",
516                                         drive->name);
517                         ireason |= ATAPI_COD;
518                         ireason &= ~ATAPI_IO;
519                 }
520         }
521
522         return ireason;
523 }
524
525 static int ide_delayed_transfer_pc(ide_drive_t *drive)
526 {
527         /* Send the actual packet */
528         drive->hwif->tp_ops->output_data(drive, NULL, drive->pc->c, 12);
529
530         /* Timeout for the packet command */
531         return WAIT_FLOPPY_CMD;
532 }
533
534 static ide_startstop_t ide_transfer_pc(ide_drive_t *drive)
535 {
536         struct ide_atapi_pc *uninitialized_var(pc);
537         ide_hwif_t *hwif = drive->hwif;
538         struct request *rq = hwif->rq;
539         ide_expiry_t *expiry;
540         unsigned int timeout;
541         int cmd_len;
542         ide_startstop_t startstop;
543         u8 ireason;
544
545         if (ide_wait_stat(&startstop, drive, ATA_DRQ, ATA_BUSY, WAIT_READY)) {
546                 printk(KERN_ERR "%s: Strange, packet command initiated yet "
547                                 "DRQ isn't asserted\n", drive->name);
548                 return startstop;
549         }
550
551         if (drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT) {
552                 if (drive->dma)
553                         drive->waiting_for_dma = 1;
554         }
555
556         if (dev_is_idecd(drive)) {
557                 /* ATAPI commands get padded out to 12 bytes minimum */
558                 cmd_len = COMMAND_SIZE(rq->cmd[0]);
559                 if (cmd_len < ATAPI_MIN_CDB_BYTES)
560                         cmd_len = ATAPI_MIN_CDB_BYTES;
561
562                 timeout = rq->timeout;
563                 expiry  = ide_cd_expiry;
564         } else {
565                 pc = drive->pc;
566
567                 cmd_len = ATAPI_MIN_CDB_BYTES;
568
569                 /*
570                  * If necessary schedule the packet transfer to occur 'timeout'
571                  * miliseconds later in ide_delayed_transfer_pc() after the
572                  * device says it's ready for a packet.
573                  */
574                 if (drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) {
575                         timeout = drive->pc_delay;
576                         expiry = &ide_delayed_transfer_pc;
577                 } else {
578                         timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
579                                                                : WAIT_TAPE_CMD;
580                         expiry = NULL;
581                 }
582
583                 ireason = ide_read_ireason(drive);
584                 if (drive->media == ide_tape)
585                         ireason = ide_wait_ireason(drive, ireason);
586
587                 if ((ireason & ATAPI_COD) == 0 || (ireason & ATAPI_IO)) {
588                         printk(KERN_ERR "%s: (IO,CoD) != (0,1) while issuing "
589                                         "a packet command\n", drive->name);
590
591                         return ide_do_reset(drive);
592                 }
593         }
594
595         hwif->expiry = expiry;
596
597         /* Set the interrupt routine */
598         ide_set_handler(drive,
599                         (dev_is_idecd(drive) ? drive->irq_handler
600                                              : ide_pc_intr),
601                         timeout);
602
603         /* Send the actual packet */
604         if ((drive->atapi_flags & IDE_AFLAG_ZIP_DRIVE) == 0)
605                 hwif->tp_ops->output_data(drive, NULL, rq->cmd, cmd_len);
606
607         /* Begin DMA, if necessary */
608         if (dev_is_idecd(drive)) {
609                 if (drive->dma)
610                         hwif->dma_ops->dma_start(drive);
611         } else {
612                 if (pc->flags & PC_FLAG_DMA_OK) {
613                         pc->flags |= PC_FLAG_DMA_IN_PROGRESS;
614                         hwif->dma_ops->dma_start(drive);
615                 }
616         }
617
618         return ide_started;
619 }
620
621 ide_startstop_t ide_issue_pc(ide_drive_t *drive, struct ide_cmd *cmd)
622 {
623         struct ide_atapi_pc *pc;
624         ide_hwif_t *hwif = drive->hwif;
625         ide_expiry_t *expiry = NULL;
626         struct request *rq = hwif->rq;
627         unsigned int timeout;
628         u32 tf_flags;
629         u16 bcount;
630         u8 drq_int = !!(drive->atapi_flags & IDE_AFLAG_DRQ_INTERRUPT);
631
632         if (dev_is_idecd(drive)) {
633                 tf_flags = IDE_TFLAG_OUT_NSECT | IDE_TFLAG_OUT_LBAL;
634                 bcount = ide_cd_get_xferlen(rq);
635                 expiry = ide_cd_expiry;
636                 timeout = ATAPI_WAIT_PC;
637
638                 if (drive->dma)
639                         drive->dma = !ide_dma_prepare(drive, cmd);
640         } else {
641                 pc = drive->pc;
642
643                 /* We haven't transferred any data yet */
644                 pc->xferred = 0;
645                 pc->cur_pos = pc->buf;
646
647                 tf_flags = IDE_TFLAG_OUT_DEVICE;
648                 bcount = ((drive->media == ide_tape) ?
649                                 pc->req_xfer :
650                                 min(pc->req_xfer, 63 * 1024));
651
652                 if (pc->flags & PC_FLAG_DMA_ERROR) {
653                         pc->flags &= ~PC_FLAG_DMA_ERROR;
654                         ide_dma_off(drive);
655                 }
656
657                 if (pc->flags & PC_FLAG_DMA_OK)
658                         drive->dma = !ide_dma_prepare(drive, cmd);
659
660                 if (!drive->dma)
661                         pc->flags &= ~PC_FLAG_DMA_OK;
662
663                 timeout = (drive->media == ide_floppy) ? WAIT_FLOPPY_CMD
664                                                        : WAIT_TAPE_CMD;
665         }
666
667         ide_init_packet_cmd(cmd, tf_flags, bcount, drive->dma);
668
669         (void)do_rw_taskfile(drive, cmd);
670
671         if (drq_int) {
672                 if (drive->dma)
673                         drive->waiting_for_dma = 0;
674                 hwif->expiry = expiry;
675         }
676
677         ide_execute_command(drive, cmd, ide_transfer_pc, timeout);
678
679         return drq_int ? ide_started : ide_transfer_pc(drive);
680 }
681 EXPORT_SYMBOL_GPL(ide_issue_pc);