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