[PATCH] 2.5.8 IDE 35

- Expand configure help options a bit
- Fix xconfig bug
- Decrease queue depth if a command takes too long to complete
- Test master/slave stuff. It works, but one device can heavily starve
   another. This is the simple approach right now, means that one device
   will wait until the other is completely idle before starting any
   commands This is not necessary since we can have queued commands on
   both devices at the same time. TODO.
- Add proc output for oldest command, just for testing.
- pci_dev compile fixes.
- Make sure ide-disk doesn't BUG if TCQ is not used, basically this was
   fixed by off-loading the using_tcq setting to ide-tcq.
- Remove warning about 'queued feature set not supported'
- Abstract ide_tcq_wait_dataphase() into a function

drivers/ide/Config.help

@@ -753,9 +753,17 @@ CONFIG_BLK_DEV_IDE_TCQ
 
   If you have such a drive, say Y here.
 
-CONFIG_BLK_DEV_IDE_TCQ_DEFAULT
-  Enabled tagged command queueing unconditionally on drives that report
-  support for it.
+CONFIG_BLK_DEV_IDE_TCQ_FULL
+  When a command completes from the drive, the SERVICE bit is checked to
+  see if other queued commands are ready to be started. Doing this
+  immediately after a command completes has a tendency to 'starve' the
+  device hardware queue, since we risk emptying the queue completely
+  before starting any new commands. This shows up during stressing the
+  drive as a /\/\/\/\ queue size balance, where we could instead try and
+  maintain a minimum queue size and get a /---------\ graph instead.
+
+  Saying Y here will attempt to always keep the queue full when possible
+  at the cost of possibly increasing command turn-around latency.
 
   Generally say Y here.
 
@@ -766,6 +774,18 @@ CONFIG_BLK_DEV_IDE_TCQ_DEPTH
   You probably just want the default of 32 here. If you enter an invalid
   number, the default value will be used.
 
+CONFIG_BLK_DEV_IDE_TCQ_DEFAULT
+  Enabled tagged command queueing unconditionally on drives that report
+  support for it. Regardless of the chosen value here, tagging can be
+  controlled at run time:
+
+  echo "using_tcq:32" > /proc/ide/hdX/settings
+
+  where any value between 1-32 selects chosen queue depth and enables
+  TCQ, and 0 disables it.
+
+  Generally say Y here.
+
 CONFIG_BLK_DEV_IT8172
   Say Y here to support the on-board IDE controller on the Integrated
   Technology Express, Inc. ITE8172 SBC.  Vendor page at

drivers/ide/Config.in

@@ -48,9 +48,10 @@ if [ "$CONFIG_BLK_DEV_IDE" != "n" ]; then
          dep_bool '    Enable DMA only for disks ' CONFIG_IDEDMA_ONLYDISK $CONFIG_IDEDMA_PCI_AUTO
 	 define_bool CONFIG_BLK_DEV_IDEDMA $CONFIG_BLK_DEV_IDEDMA_PCI
 	 dep_bool '    ATA tagged command queueing' CONFIG_BLK_DEV_IDE_TCQ $CONFIG_BLK_DEV_IDEDMA_PCI
+	 dep_bool '      Attempt to keep queue full' CONFIG_BLK_DEV_IDE_TCQ_FULL $CONFIG_BLK_DEV_IDE_TCQ
 	 dep_bool '      TCQ on by default' CONFIG_BLK_DEV_IDE_TCQ_DEFAULT $CONFIG_BLK_DEV_IDE_TCQ
-	   if [ $CONFIG_BLK_DEV_IDE_TCQ_DEFAULT != "n" ]; then
-		int '      Default queue depth' CONFIG_BLK_DEV_IDE_TCQ_DEPTH 32
+	 if [ "$CONFIG_BLK_DEV_IDE_TCQ" != "n" ]; then
+	    int '      Default queue depth' CONFIG_BLK_DEV_IDE_TCQ_DEPTH 8
 	 fi
 	 dep_bool '    ATA Work(s) In Progress (EXPERIMENTAL)' CONFIG_IDEDMA_PCI_WIP $CONFIG_BLK_DEV_IDEDMA_PCI $CONFIG_EXPERIMENTAL
 	 dep_bool '    Good-Bad DMA Model-Firmware (WIP)' CONFIG_IDEDMA_NEW_DRIVE_LISTINGS $CONFIG_IDEDMA_PCI_WIP

drivers/ide/ide-disk.c

@@ -107,10 +107,7 @@ static u8 get_command(ide_drive_t *drive, int cmd)
 	 * 48-bit commands are pretty sanely laid out
 	 */
 	if (lba48bit) {
-		if (cmd == READ)
-			command = WIN_READ_EXT;
-		else
-			command = WIN_WRITE_EXT;
+		command = cmd == READ ? WIN_READ_EXT : WIN_WRITE_EXT;
 
 		if (drive->using_dma) {
 			command++;		/* WIN_*DMA_EXT */
@@ -118,7 +115,10 @@ static u8 get_command(ide_drive_t *drive, int cmd)
 				command++;	/* WIN_*DMA_QUEUED_EXT */
 		} else if (drive->mult_count)
 			command += 5;		/* WIN_MULT*_EXT */
-	} else {
+
+		return command;
+	}
+
 	/*
 	 * 28-bit commands seem not to be, though...
 	 */
@@ -143,7 +143,6 @@ static u8 get_command(ide_drive_t *drive, int cmd)
 		else
 			command = WIN_WRITE;
 	}
-	}
 
 	return command;
 }
@@ -895,24 +894,24 @@ static int proc_idedisk_read_tcq
 
 		__set_bit(i, &tag_mask);
 		len += sprintf(out+len, "%d, ", i);
-		if (ar->ar_time > max_jif)
-			max_jif = ar->ar_time;
+		if (cur_jif - ar->ar_time > max_jif)
+			max_jif = cur_jif - ar->ar_time;
 		cmds++;
 	}
 	len += sprintf(out+len, "]\n");
 
+	len += sprintf(out+len, "Queue:\t\t\treleased [ %d ] - started [ %d ]\n", drive->tcq->immed_rel, drive->tcq->immed_comp);
+
 	if (drive->tcq->queued != cmds)
-		len += sprintf(out+len, "pending request and queue count mismatch (%d)\n", cmds);
+		len += sprintf(out+len, "pending request and queue count mismatch (counted: %d)\n", cmds);
 
 	if (tag_mask != drive->tcq->tag_mask)
 		len += sprintf(out+len, "tag masks differ (counted %lx != %lx\n", tag_mask, drive->tcq->tag_mask);
 
 	len += sprintf(out+len, "DMA status:\t\t%srunning\n", test_bit(IDE_DMA, &HWGROUP(drive)->flags) ? "" : "not ");
 
-	if (max_jif)
-		len += sprintf(out+len, "Oldest command:\t\t%lu\n", cur_jif - max_jif);
-
-	len += sprintf(out+len, "immed rel %d, immed comp %d\n", drive->tcq->immed_rel, drive->tcq->immed_comp);
+	len += sprintf(out+len, "Oldest command:\t\t%lu jiffies\n", max_jif);
+	len += sprintf(out+len, "Oldest command ever:\t%lu\n", drive->tcq->oldest_command);
 
 	drive->tcq->max_last_depth = 0;
 
@@ -1017,8 +1016,10 @@ static int set_using_tcq(ide_drive_t *drive, int arg)
 		return -EPERM;
 	if (!drive->channel->dmaproc)
 		return -EPERM;
+	if (arg == drive->queue_depth && drive->using_tcq)
+		return 0;
 
-	drive->using_tcq = arg;
+	drive->queue_depth = arg ? arg : 1;
 	if (drive->channel->dmaproc(arg ? ide_dma_queued_on : ide_dma_queued_off, drive))
 		return -EIO;
 

drivers/ide/ide-dma.c

@@ -610,9 +610,6 @@ int ide_dmaproc (ide_dma_action_t func, ide_drive_t *drive)
 		case ide_dma_check:
 			return config_drive_for_dma (drive);
 		case ide_dma_begin:
-#ifdef DEBUG
-			printk("ide_dma_begin: from %p\n", __builtin_return_address(0));
-#endif
 			if (test_and_set_bit(IDE_DMA, &HWGROUP(drive)->flags))
 				BUG();
 			/* Note that this is done *after* the cmd has
@@ -634,14 +631,13 @@ int ide_dmaproc (ide_dma_action_t func, ide_drive_t *drive)
 		case ide_dma_read:
 			reading = 1 << 3;
 		case ide_dma_write:
-			ar = HWGROUP(drive)->rq->special;
+			ar = IDE_CUR_AR(drive);
 
 			if (ide_start_dma(hwif, drive, func))
 				return 1;
 
 			if (drive->type != ATA_DISK)
 				return 0;
-
 			BUG_ON(HWGROUP(drive)->handler);
 			ide_set_handler(drive, &ide_dma_intr, WAIT_CMD, dma_timer_expiry);	/* issue cmd to drive */
 			if ((ar->ar_rq->flags & REQ_DRIVE_TASKFILE) &&
@@ -655,20 +651,13 @@ int ide_dmaproc (ide_dma_action_t func, ide_drive_t *drive)
 			}
 			return hwif->dmaproc(ide_dma_begin, drive);
 		case ide_dma_end: /* returns 1 on error, 0 otherwise */
-#ifdef DEBUG
-			printk("ide_dma_end: from %p\n", __builtin_return_address(0));
-#endif
-			if (!test_and_clear_bit(IDE_DMA, &HWGROUP(drive)->flags)) {
-				printk("ide_dma_end: dma not going? %p\n", __builtin_return_address(0));
-				return 1;
-			}
+			if (!test_and_clear_bit(IDE_DMA, &HWGROUP(drive)->flags))
+				BUG();
 			drive->waiting_for_dma = 0;
 			outb(inb(dma_base)&~1, dma_base);	/* stop DMA */
 			dma_stat = inb(dma_base+2);	/* get DMA status */
 			outb(dma_stat|6, dma_base+2);	/* clear the INTR & ERROR bits */
 			ide_destroy_dmatable(drive);	/* purge DMA mappings */
-			if (drive->tcq)
-				IDE_SET_CUR_TAG(drive, -1);
 			return (dma_stat & 7) != 4 ? (0x10 | dma_stat) : 0;	/* verify good DMA status */
 		case ide_dma_test_irq: /* returns 1 if dma irq issued, 0 otherwise */
 			dma_stat = inb(dma_base+2);

drivers/ide/ide-probe.c

@@ -192,19 +192,16 @@ static inline void do_identify (ide_drive_t *drive, byte cmd)
 	/*
 	 * it's an ata drive, build command list
 	 */
-#ifndef CONFIG_BLK_DEV_IDE_TCQ
 	drive->queue_depth = 1;
+#ifdef CONFIG_BLK_DEV_IDE_TCQ_DEPTH
+	drive->queue_depth = CONFIG_BLK_DEV_IDE_TCQ_DEPTH;
 #else
-# ifndef CONFIG_BLK_DEV_IDE_TCQ_DEPTH
-#  define CONFIG_BLK_DEV_IDE_TCQ_DEPTH 1
-# endif
 	drive->queue_depth = drive->id->queue_depth + 1;
-	if (drive->queue_depth > CONFIG_BLK_DEV_IDE_TCQ_DEPTH)
-		drive->queue_depth = CONFIG_BLK_DEV_IDE_TCQ_DEPTH;
+#endif
 	if (drive->queue_depth < 1 || drive->queue_depth > IDE_MAX_TAG)
 		drive->queue_depth = IDE_MAX_TAG;
-#endif
-	if (ide_build_commandlist(drive))
+
+	if (ide_init_commandlist(drive))
 		goto err_misc;
 
 	return;

drivers/ide/ide-tcq.c

@@ -29,9 +29,11 @@
 #include <asm/delay.h>
 
 /*
- * warning: it will be _very_ verbose if set to 1
+ * warning: it will be _very_ verbose if defined
  */
-#if 0
+#undef IDE_TCQ_DEBUG
+
+#ifdef IDE_TCQ_DEBUG
 #define TCQ_PRINTK printk
 #else
 #define TCQ_PRINTK(x...)
@@ -49,13 +51,18 @@
  */
 #undef IDE_TCQ_FIDDLE_SI
 
-int ide_tcq_end(ide_drive_t *drive);
+/*
+ * wait for data phase before starting DMA or not
+ */
+#undef IDE_TCQ_WAIT_DATAPHASE
+
 ide_startstop_t ide_dmaq_intr(ide_drive_t *drive);
+ide_startstop_t ide_service(ide_drive_t *drive);
 
 static inline void drive_ctl_nien(ide_drive_t *drive, int clear)
 {
 #ifdef IDE_TCQ_NIEN
-	int mask = clear ? 0 : 2;
+	int mask = clear ? 0x00 : 0x02;
 
 	if (IDE_CONTROL_REG)
 		OUT_BYTE(drive->ctl | mask, IDE_CONTROL_REG);
@@ -142,7 +149,7 @@ void ide_tcq_intr_timeout(unsigned long data)
 
 	spin_lock_irqsave(&ide_lock, flags);
 
-	if (test_bit(IDE_BUSY, &hwgroup->flags))
+	if (test_and_set_bit(IDE_BUSY, &hwgroup->flags))
 		printk("ide_tcq_intr_timeout: hwgroup not busy\n");
 	if (hwgroup->handler == NULL)
 		printk("ide_tcq_intr_timeout: missing isr!\n");
@@ -151,6 +158,13 @@ void ide_tcq_intr_timeout(unsigned long data)
 
 	spin_unlock_irqrestore(&ide_lock, flags);
 
+	/*
+	 * if pending commands, try service before giving up
+	 */
+	if (ide_pending_commands(drive) && (GET_STAT() & SERVICE_STAT))
+		if (ide_service(drive) == ide_started)
+			return;
+
 	if (drive)
 		ide_tcq_invalidate_queue(drive);
 }
@@ -192,6 +206,7 @@ int ide_tcq_wait_altstat(ide_drive_t *drive, byte *stat, byte busy_mask)
 
 		if (unlikely(i++ > IDE_TCQ_WAIT))
 			return 1;
+
 	} while ((*stat = GET_ALTSTAT()) & busy_mask);
 
 	return 0;
@@ -206,7 +221,12 @@ int ide_tcq_wait_altstat(ide_drive_t *drive, byte *stat, byte busy_mask)
 ide_startstop_t ide_service(ide_drive_t *drive)
 {
 	struct ata_request *ar;
-	byte feat, tag, stat;
+	byte feat, stat;
+	int tag;
+
+	TCQ_PRINTK("%s: started service\n", drive->name);
+
+	drive->service_pending = 0;
 
 	if (test_bit(IDE_DMA, &HWGROUP(drive)->flags))
 		printk("ide_service: DMA in progress\n");
@@ -238,9 +258,9 @@ ide_startstop_t ide_service(ide_drive_t *drive)
 	 * FIXME, invalidate queue
 	 */
 	if (stat & ERR_STAT) {
-		printk("%s: error SERVICING drive (%x)\n", drive->name, stat);
 		ide_dump_status(drive, "ide_service", stat);
-		return ide_tcq_end(drive);
+		ide_tcq_invalidate_queue(drive);
+		return ide_stopped;
 	}
 
 	/*
@@ -248,7 +268,7 @@ ide_startstop_t ide_service(ide_drive_t *drive)
 	 */
 	if ((feat = GET_FEAT()) & NSEC_REL) {
 		printk("%s: release in service\n", drive->name);
-		IDE_SET_CUR_TAG(drive, -1);
+		IDE_SET_CUR_TAG(drive, IDE_INACTIVE_TAG);
 		return ide_stopped;
 	}
 
@@ -265,6 +285,8 @@ ide_startstop_t ide_service(ide_drive_t *drive)
 		return ide_stopped;
 	}
 
+	HWGROUP(drive)->rq = ar->ar_rq;
+
 	/*
 	 * we'll start a dma read or write, device will trigger
 	 * interrupt to indicate end of transfer, release is not allowed
@@ -287,6 +309,8 @@ ide_startstop_t ide_check_service(ide_drive_t *drive)
 {
 	byte stat;
 
+	TCQ_PRINTK("%s: ide_check_service\n", drive->name);
+
 	if (!ide_pending_commands(drive))
 		return ide_stopped;
 
@@ -300,40 +324,14 @@ ide_startstop_t ide_check_service(ide_drive_t *drive)
 	return ide_started;
 }
 
-int ide_tcq_end(ide_drive_t *drive)
-{
-	byte stat = GET_STAT();
-
-	if (stat & ERR_STAT) {
-		ide_dump_status(drive, "ide_tcq_end", stat);
-		ide_tcq_invalidate_queue(drive);
-		return ide_stopped;
-	} else if (stat & SERVICE_STAT) {
-		TCQ_PRINTK("ide_tcq_end: serv stat=%x\n", stat);
-		return ide_service(drive);
-	}
-
-	TCQ_PRINTK("ide_tcq_end: stat=%x, feat=%x\n", stat, GET_FEAT());
-	return ide_stopped;
-}
-
 ide_startstop_t ide_dmaq_complete(ide_drive_t *drive, byte stat)
 {
-	struct ata_request *ar;
+	struct ata_request *ar = IDE_CUR_TAG(drive);
 	byte dma_stat;
 
-#if 0
-	byte feat = GET_FEAT();
-
-	if ((feat & (NSEC_CD | NSEC_IO)) != (NSEC_CD | NSEC_IO))
-		printk("%s: C/D | I/O not set\n", drive->name);
-#endif
-
 	/*
 	 * transfer was in progress, stop DMA engine
 	 */
-	ar = IDE_CUR_TAG(drive);
-
 	dma_stat = drive->channel->dmaproc(ide_dma_end, drive);
 
 	/*
@@ -352,7 +350,23 @@ ide_startstop_t ide_dmaq_complete(ide_drive_t *drive, byte stat)
 	TCQ_PRINTK("ide_dmaq_intr: ending %p, tag %d\n", ar, ar->ar_tag);
 	ide_end_queued_request(drive, !dma_stat, ar->ar_rq);
 
-	IDE_SET_CUR_TAG(drive, -1);
+	IDE_SET_CUR_TAG(drive, IDE_INACTIVE_TAG);
+
+	/*
+	 * keep the queue full, or honor SERVICE? note that this may race
+	 * and no new command will be started, in which case idedisk_do_request
+	 * will notice and do the service check
+	 */
+#if CONFIG_BLK_DEV_IDE_TCQ_FULL
+	if (!drive->service_pending && (ide_pending_commands(drive) > 1)) {
+		if (!blk_queue_empty(&drive->queue)) {
+			drive->service_pending = 1;
+			ide_tcq_set_intr(HWGROUP(drive), ide_dmaq_intr);
+			return ide_released;
+		}
+	}
+#endif
+
 	return ide_check_service(drive);
 }
 
@@ -376,7 +390,7 @@ ide_startstop_t ide_dmaq_intr(ide_drive_t *drive)
 	 * if a command completion interrupt is pending, do that first and
 	 * check service afterwards
 	 */
-	if (drive->tcq->active_tag != -1)
+	if (drive->tcq->active_tag != IDE_INACTIVE_TAG)
 		return ide_dmaq_complete(drive, stat);
 
 	/*
@@ -403,10 +417,8 @@ static int ide_tcq_configure(ide_drive_t *drive)
 	 * bit 14 and 1 must be set in word 83 of the device id to indicate
 	 * support for dma queued protocol
 	 */
-	if ((drive->id->command_set_2 & tcq_supp) != tcq_supp) {
-		printk("%s: queued feature set not supported\n", drive->name);
-		return 1;
-	}
+	if ((drive->id->command_set_2 & tcq_supp) != tcq_supp)
+		return -EIO;
 
 	memset(&args, 0, sizeof(args));
 	args.taskfile.feature = SETFEATURES_EN_WCACHE;
@@ -446,6 +458,16 @@ static int ide_tcq_configure(ide_drive_t *drive)
 		return 1;
 	}
 #endif
+
+	if (!drive->tcq) {
+		drive->tcq = kmalloc(sizeof(ide_tag_info_t), GFP_ATOMIC);
+		if (!drive->tcq)
+			return -ENOMEM;
+
+		memset(drive->tcq, 0, sizeof(ide_tag_info_t));
+		drive->tcq->active_tag = IDE_INACTIVE_TAG;
+	}
+
 	return 0;
 }
 
@@ -461,26 +483,33 @@ static int ide_enable_queued(ide_drive_t *drive, int on)
 	if (!on) {
 		printk("%s: TCQ disabled\n", drive->name);
 		drive->using_tcq = 0;
-
 		return 0;
-	} else if (drive->using_tcq) {
-		drive->queue_depth = drive->using_tcq;
-
-		goto out;
 	}
 
 	if (ide_tcq_configure(drive)) {
 		drive->using_tcq = 0;
-
 		return 1;
 	}
 
-out:
-	drive->tcq->max_depth = 0;
+	if (ide_build_commandlist(drive))
+		return 1;
 
 	printk("%s: tagged command queueing enabled, command queue depth %d\n", drive->name, drive->queue_depth);
 	drive->using_tcq = 1;
+	drive->tcq->max_depth = 0;
+	return 0;
+}
+
+int ide_tcq_wait_dataphase(ide_drive_t *drive)
+{
+#ifdef IDE_TCQ_WAIT_DATAPHASE
+	ide_startstop_t foo;
 
+	if (ide_wait_stat(&startstop, drive, READY_STAT | DRQ_STAT, BUSY_STAT, WAIT_READY)) {
+		printk("%s: timeout waiting for data phase\n", drive->name);
+		return 1;
+	}
+#endif
 	return 0;
 }
 
@@ -488,7 +517,6 @@ int ide_tcq_dmaproc(ide_dma_action_t func, ide_drive_t *drive)
 {
 	struct ata_channel *hwif = drive->channel;
 	unsigned int reading = 0, enable_tcq = 1;
-	ide_startstop_t startstop;
 	struct ata_request *ar;
 	byte stat, feat;
 
@@ -501,15 +529,13 @@ int ide_tcq_dmaproc(ide_dma_action_t func, ide_drive_t *drive)
 			reading = 1 << 3;
 		case ide_dma_write_queued:
 			TCQ_PRINTK("ide_dma: setting up queued %d\n", drive->tcq->active_tag);
-			BUG_ON(drive->tcq->active_tag == -1);
+			BUG_ON(drive->tcq->active_tag == IDE_INACTIVE_TAG);
 
 			if (!test_bit(IDE_BUSY, &HWGROUP(drive)->flags))
 				printk("queued_rw: IDE_BUSY not set\n");
 
-			if (ide_wait_stat(&startstop, drive, READY_STAT | DRQ_STAT, BUSY_STAT, WAIT_READY)) {
-				printk("%s: timeout waiting for data phase\n", drive->name);
-				return startstop;
-			}
+			if (ide_tcq_wait_dataphase(drive))
+				return ide_stopped;
 
 			if (ide_start_dma(hwif, drive, func))
 				return 1;
@@ -521,7 +547,7 @@ int ide_tcq_dmaproc(ide_dma_action_t func, ide_drive_t *drive)
 			 * start a queued command from scratch
 			 */
 		case ide_dma_queued_start:
-			BUG_ON(drive->tcq->active_tag == -1);
+			BUG_ON(drive->tcq->active_tag == IDE_INACTIVE_TAG);
 			ar = IDE_CUR_TAG(drive);
 
 			/*
@@ -540,14 +566,19 @@ int ide_tcq_dmaproc(ide_dma_action_t func, ide_drive_t *drive)
 			drive_ctl_nien(drive, 0);
 
 			if (stat & ERR_STAT) {
-				printk("ide_dma_queued_start: abort (stat=%x)\n", stat);
+				ide_dump_status(drive, "tcq_start", stat);
 				return ide_stopped;
 			}
 
+			/*
+			 * drive released the bus, clear active tag and
+			 * check for service
+			 */
 			if ((feat = GET_FEAT()) & NSEC_REL) {
+				IDE_SET_CUR_TAG(drive, IDE_INACTIVE_TAG);
 				drive->tcq->immed_rel++;
+
 				TCQ_PRINTK("REL in queued_start\n");
-				IDE_SET_CUR_TAG(drive, -1);
 
 				if ((stat = GET_STAT()) & SERVICE_STAT)
 					return ide_service(drive);
@@ -558,21 +589,24 @@ int ide_tcq_dmaproc(ide_dma_action_t func, ide_drive_t *drive)
 
 			drive->tcq->immed_comp++;
 
-			if (ide_wait_stat(&startstop, drive, READY_STAT | DRQ_STAT, BUSY_STAT, WAIT_READY)) {
-				printk("%s: timeout waiting for data phase\n", drive->name);
-				return startstop;
-			}
+			if (ide_tcq_wait_dataphase(drive))
+				return ide_stopped;
 
 			if (ide_start_dma(hwif, drive, func))
 				return ide_stopped;
 
+			/*
+			 * need to arm handler before starting dma engine,
+			 * transfer could complete right away
+			 */
+			ide_tcq_set_intr(HWGROUP(drive), ide_dmaq_intr);
+
 			if (hwif->dmaproc(ide_dma_begin, drive))
 				return ide_stopped;
 
 			/*
 			 * wait for SERVICE or completion interrupt
 			 */
-			ide_tcq_set_intr(HWGROUP(drive), ide_dmaq_intr);
 			return ide_started;
 
 		case ide_dma_queued_off:
@@ -590,6 +624,10 @@ int ide_build_sglist (struct ata_channel *hwif, struct request *rq);
 ide_startstop_t ide_start_tag(ide_dma_action_t func, ide_drive_t *drive,
 			      struct ata_request *ar)
 {
+	ide_startstop_t startstop;
+
+	TCQ_PRINTK("%s: ide_start_tag: begin tag %p/%d, rq %p\n", drive->name,ar,ar->ar_tag, ar->ar_rq);
+
 	/*
 	 * do this now, no need to run that with interrupts disabled
 	 */
@@ -597,5 +635,14 @@ ide_startstop_t ide_start_tag(ide_dma_action_t func, ide_drive_t *drive,
 		return ide_stopped;
 
 	IDE_SET_CUR_TAG(drive, ar->ar_tag);
-	return ide_tcq_dmaproc(func, drive);
+	HWGROUP(drive)->rq = ar->ar_rq;
+
+	startstop = ide_tcq_dmaproc(func, drive);
+
+	if (unlikely(startstop == ide_stopped)) {
+		IDE_SET_CUR_TAG(drive, IDE_INACTIVE_TAG);
+		HWGROUP(drive)->rq = NULL;
+	}
+
+	return startstop;
 }

drivers/ide/ide.c

@@ -381,8 +381,23 @@ void ide_end_queued_request(ide_drive_t *drive, int uptodate, struct request *rq
 		add_blkdev_randomness(major(rq->rq_dev));
 
 		spin_lock_irqsave(&ide_lock, flags);
+
+		if ((jiffies - ar->ar_time > ATA_AR_MAX_TURNAROUND) && drive->queue_depth > 1) {
+			printk("%s: exceeded max command turn-around time (%d seconds)\n", drive->name, ATA_AR_MAX_TURNAROUND / HZ);
+			drive->queue_depth >>= 1;
+		}
+
+		if (jiffies - ar->ar_time > drive->tcq->oldest_command)
+			drive->tcq->oldest_command = jiffies - ar->ar_time;
+
 		ata_ar_put(drive, ar);
 		end_that_request_last(rq);
+		/*
+		 * IDE_SET_CUR_TAG(drive, IDE_INACTIVE_TAG) will do this
+		 * too, but it really belongs here. assumes that the
+		 * ended request is the active one.
+		 */
+		HWGROUP(drive)->rq = NULL;
 		spin_unlock_irqrestore(&ide_lock, flags);
 	}
 }
@@ -770,8 +785,7 @@ void ide_end_drive_cmd(ide_drive_t *drive, byte stat, byte err)
 		struct ata_taskfile *args = &ar->ar_task;
 
 		rq->errors = !OK_STAT(stat, READY_STAT, BAD_STAT);
-		if (args && args->taskfile.command == WIN_NOP)
-			printk(KERN_INFO "%s: NOP completed\n", __FUNCTION__);
+
 		if (args) {
 			args->taskfile.feature = err;
 			args->taskfile.sector_count = IN_BYTE(IDE_NSECTOR_REG);
@@ -1101,11 +1115,7 @@ static ide_startstop_t start_request(ide_drive_t *drive, struct request *rq)
 	while ((read_timer() - hwif->last_time) < DISK_RECOVERY_TIME);
 #endif
 
-	if (test_bit(IDE_DMA, &HWGROUP(drive)->flags))
-		printk("start_request: auch, DMA in progress 1\n");
 	SELECT_DRIVE(hwif, drive);
-	if (test_bit(IDE_DMA, &HWGROUP(drive)->flags))
-		printk("start_request: auch, DMA in progress 2\n");
 	if (ide_wait_stat(&startstop, drive, drive->ready_stat,
 			  BUSY_STAT|DRQ_STAT, WAIT_READY)) {
 		printk(KERN_WARNING "%s: drive not ready for command\n", drive->name);
@@ -1277,93 +1287,84 @@ static inline ide_drive_t *choose_drive(ide_hwgroup_t *hwgroup)
 	return best;
 }
 
-/*
- * Issue a new request to a drive from hwgroup
- * Caller must have already done spin_lock_irqsave(&ide_lock, ...)
- *
- * A hwgroup is a serialized group of IDE interfaces.  Usually there is
- * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
- * may have both interfaces in a single hwgroup to "serialize" access.
- * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
- * together into one hwgroup for serialized access.
- *
- * Note also that several hwgroups can end up sharing a single IRQ,
- * possibly along with many other devices.  This is especially common in
- * PCI-based systems with off-board IDE controller cards.
- *
- * The IDE driver uses the queue spinlock to protect access to the request
- * queues.
- *
- * The first thread into the driver for a particular hwgroup sets the
- * hwgroup->flags IDE_BUSY flag to indicate that this hwgroup is now active,
- * and then initiates processing of the top request from the request queue.
- *
- * Other threads attempting entry notice the busy setting, and will simply
- * queue their new requests and exit immediately.  Note that hwgroup->flags
- * remains busy even when the driver is merely awaiting the next interrupt.
- * Thus, the meaning is "this hwgroup is busy processing a request".
- *
- * When processing of a request completes, the completing thread or IRQ-handler
- * will start the next request from the queue.  If no more work remains,
- * the driver will clear the hwgroup->flags IDE_BUSY flag and exit.
- */
-static void ide_do_request(ide_hwgroup_t *hwgroup, int masked_irq)
+static ide_drive_t *ide_choose_drive(ide_hwgroup_t *hwgroup)
 {
-	ide_drive_t *drive;
-	struct ata_channel *hwif;
-	ide_startstop_t	startstop;
-	struct request	*rq;
-
-	ide_get_lock(&ide_intr_lock, ide_intr, hwgroup);/* for atari only: POSSIBLY BROKEN HERE(?) */
+	ide_drive_t *drive = choose_drive(hwgroup);
+	unsigned long sleep = 0;
 
-	__cli();	/* necessary paranoia: ensure IRQs are masked on local CPU */
+	if (drive)
+		return drive;
 
-	while (!test_and_set_bit(IDE_BUSY, &hwgroup->flags)) {
-		drive = choose_drive(hwgroup);
-		if (drive == NULL) {
-			unsigned long sleep = 0;
 	hwgroup->rq = NULL;
 	drive = hwgroup->drive;
 	do {
 		if (drive->PADAM_sleep && (!sleep || time_after(sleep, drive->PADAM_sleep)))
 			sleep = drive->PADAM_sleep;
 	} while ((drive = drive->next) != hwgroup->drive);
+
 	if (sleep) {
 		/*
-				 * Take a short snooze, and then wake up this hwgroup again.
-				 * This gives other hwgroups on the same a chance to
-				 * play fairly with us, just in case there are big differences
-				 * in relative throughputs.. don't want to hog the cpu too much.
+		 * Take a short snooze, and then wake up this hwgroup
+		 * again.  This gives other hwgroups on the same a
+		 * chance to play fairly with us, just in case there
+		 * are big differences in relative throughputs.. don't
+		 * want to hog the cpu too much.
 		 */
 		if (0 < (signed long)(jiffies + WAIT_MIN_SLEEP - sleep))
 			sleep = jiffies + WAIT_MIN_SLEEP;
-#if 1
+
 		if (timer_pending(&hwgroup->timer))
 			printk("ide_set_handler: timer already active\n");
-#endif
+
 		set_bit(IDE_SLEEP, &hwgroup->flags);
 		mod_timer(&hwgroup->timer, sleep);
-				/* we purposely leave hwgroup busy while sleeping */
+		/* we purposely leave hwgroup busy while
+		 * sleeping */
 	} else {
-				/* Ugly, but how can we sleep for the lock otherwise? perhaps from tq_disk? */
+		/* Ugly, but how can we sleep for the lock
+		 * otherwise? perhaps from tq_disk? */
 		ide_release_lock(&ide_intr_lock);/* for atari only */
 		clear_bit(IDE_BUSY, &hwgroup->flags);
 	}
-			return;		/* no more work for this hwgroup (for now) */
-		}
-		hwif = drive->channel;
-		if (hwgroup->hwif->sharing_irq && hwif != hwgroup->hwif && hwif->io_ports[IDE_CONTROL_OFFSET]) {
-			/* set nIEN for previous hwif */
 
-			if (hwif->intrproc)
-				hwif->intrproc(drive);
-			else
-				OUT_BYTE((drive)->ctl|2, hwif->io_ports[IDE_CONTROL_OFFSET]);
+	return NULL;
+}
+
+#ifdef CONFIG_BLK_DEV_IDE_TCQ
+ide_startstop_t ide_check_service(ide_drive_t *drive);
+#else
+#define ide_check_service(drive)	(ide_stopped)
+#endif
+
+/*
+ * feed commands to a drive until it barfs. used to be part of ide_do_request.
+ * called with ide_lock/DRIVE_LOCK held and busy hwgroup
+ */
+static void ide_queue_commands(ide_drive_t *drive, int masked_irq)
+{
+	ide_hwgroup_t *hwgroup = HWGROUP(drive);
+	ide_startstop_t startstop = -1;
+	struct request *rq;
+	int do_service = 0;
+
+	do {
+		rq = NULL;
+
+		if (!test_bit(IDE_BUSY, &hwgroup->flags))
+			printk("%s: hwgroup not busy while queueing\n", drive->name);
+
+		/*
+		 * abort early if we can't queue another command. for non
+		 * tcq, ide_can_queue is always 1 since we never get here
+		 * unless the drive is idle.
+		 */
+		if (!ide_can_queue(drive)) {
+			if (!ide_pending_commands(drive))
+				clear_bit(IDE_BUSY, &hwgroup->flags);
+			break;
 		}
-		hwgroup->hwif = hwif;
-		hwgroup->drive = drive;
+
 		drive->PADAM_sleep = 0;
-queue_next:
 		drive->PADAM_service_start = jiffies;
 
 		if (test_bit(IDE_DMA, &hwgroup->flags)) {
@@ -1383,43 +1384,135 @@ static void ide_do_request(ide_hwgroup_t *hwgroup, int masked_irq)
 			break;
 		}
 
-		/*
-		 * just continuing an interrupted request maybe
-		 */
-		rq = hwgroup->rq = elv_next_request(&drive->queue);
-
-		if (!rq) {
+		if (!(rq = elv_next_request(&drive->queue))) {
 			if (!ide_pending_commands(drive))
-				clear_bit(IDE_BUSY, &HWGROUP(drive)->flags);
+				clear_bit(IDE_BUSY, &hwgroup->flags);
+			hwgroup->rq = NULL;
 			break;
 		}
 
+		/*
+		 * if there are queued commands, we can't start a non-fs
+		 * request (really, a non-queuable command) until the
+		 * queue is empty
+		 */
+		if (!(rq->flags & REQ_CMD) && ide_pending_commands(drive))
+			break;
+
+		hwgroup->rq = rq;
+
+service:
 		/*
 		 * Some systems have trouble with IDE IRQs arriving while
 		 * the driver is still setting things up.  So, here we disable
-		 * the IRQ used by this interface while the request is being started.
-		 * This may look bad at first, but pretty much the same thing
-		 * happens anyway when any interrupt comes in, IDE or otherwise
-		 *  -- the kernel masks the IRQ while it is being handled.
+		 * the IRQ used by this interface while the request is being
+		 * started.  This may look bad at first, but pretty much the
+		 * same thing happens anyway when any interrupt comes in, IDE
+		 * or otherwise -- the kernel masks the IRQ while it is being
+		 * handled.
 		 */
-		if (masked_irq && hwif->irq != masked_irq)
-			disable_irq_nosync(hwif->irq);
+		if (masked_irq && HWIF(drive)->irq != masked_irq)
+			disable_irq_nosync(HWIF(drive)->irq);
 
 		spin_unlock(&ide_lock);
 		ide__sti();	/* allow other IRQs while we start this request */
+		if (!do_service)
 			startstop = start_request(drive, rq);
+		else
+			startstop = ide_check_service(drive);
 
 		spin_lock_irq(&ide_lock);
-		if (masked_irq && hwif->irq != masked_irq)
-			enable_irq(hwif->irq);
+		if (masked_irq && HWIF(drive)->irq != masked_irq)
+			enable_irq(HWIF(drive)->irq);
 
-		if (startstop == ide_released)
-			goto queue_next;
-		else if (startstop == ide_stopped) {
-			if (test_bit(IDE_DMA, &hwgroup->flags))
-				printk("2nd illegal clear\n");
-			clear_bit(IDE_BUSY, &hwgroup->flags);
+		/*
+		 * command started, we are busy
+		 */
+		if (startstop == ide_started)
+			break;
+
+		/*
+		 * start_request() can return either ide_stopped (no command
+		 * was started), ide_started (command started, don't queue
+		 * more), or ide_released (command started, try and queue
+		 * more).
+		 */
+#if 0
+		if (startstop == ide_stopped)
+			set_bit(IDE_BUSY, &hwgroup->flags);
+#endif
+
+	} while (1);
+
+	if (startstop == ide_started)
+		return;
+
+	if ((do_service = drive->service_pending))
+		goto service;
+}
+
+/*
+ * Issue a new request to a drive from hwgroup
+ * Caller must have already done spin_lock_irqsave(&ide_lock, ...)
+ *
+ * A hwgroup is a serialized group of IDE interfaces.  Usually there is
+ * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
+ * may have both interfaces in a single hwgroup to "serialize" access.
+ * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
+ * together into one hwgroup for serialized access.
+ *
+ * Note also that several hwgroups can end up sharing a single IRQ,
+ * possibly along with many other devices.  This is especially common in
+ * PCI-based systems with off-board IDE controller cards.
+ *
+ * The IDE driver uses the queue spinlock to protect access to the request
+ * queues.
+ *
+ * The first thread into the driver for a particular hwgroup sets the
+ * hwgroup->flags IDE_BUSY flag to indicate that this hwgroup is now active,
+ * and then initiates processing of the top request from the request queue.
+ *
+ * Other threads attempting entry notice the busy setting, and will simply
+ * queue their new requests and exit immediately.  Note that hwgroup->flags
+ * remains busy even when the driver is merely awaiting the next interrupt.
+ * Thus, the meaning is "this hwgroup is busy processing a request".
+ *
+ * When processing of a request completes, the completing thread or IRQ-handler
+ * will start the next request from the queue.  If no more work remains,
+ * the driver will clear the hwgroup->flags IDE_BUSY flag and exit.
+ */
+static void ide_do_request(ide_hwgroup_t *hwgroup, int masked_irq)
+{
+	ide_drive_t *drive;
+	struct ata_channel *hwif;
+
+	ide_get_lock(&ide_intr_lock, ide_intr, hwgroup);/* for atari only: POSSIBLY BROKEN HERE(?) */
+
+	__cli();	/* necessary paranoia: ensure IRQs are masked on local CPU */
+
+	while (!test_and_set_bit(IDE_BUSY, &hwgroup->flags)) {
+
+		/*
+		 * will clear IDE_BUSY, if appropriate
+		 */
+		if ((drive = ide_choose_drive(hwgroup)) == NULL)
+			break;
+
+		hwif = drive->channel;
+		if (hwgroup->hwif->sharing_irq && hwif != hwgroup->hwif && IDE_CONTROL_REG) {
+			/* set nIEN for previous hwif */
+			if (hwif->intrproc)
+				hwif->intrproc(drive);
+			else
+				OUT_BYTE(drive->ctl|2, IDE_CONTROL_REG);
 		}
+		hwgroup->hwif = hwif;
+		hwgroup->drive = drive;
+
+		/*
+		 * main queueing loop
+		 */
+		ide_queue_commands(drive, masked_irq);
 	}
 }
 
@@ -1673,6 +1766,7 @@ void ide_intr(int irq, void *dev_id, struct pt_regs *regs)
 		goto out_lock;
 
 	if ((handler = hwgroup->handler) == NULL || hwgroup->poll_timeout != 0) {
+		printk("ide: unexpected interrupt\n");
 		/*
 		 * Not expecting an interrupt from this drive.
 		 * That means this could be:
@@ -1751,7 +1845,8 @@ void ide_intr(int irq, void *dev_id, struct pt_regs *regs)
 		} else {
 			printk("%s: ide_intr: huh? expected NULL handler on exit\n", drive->name);
 		}
-	}
+	} else if (startstop == ide_released)
+		ide_queue_commands(drive, hwif->irq);
 
 out_lock:
 	spin_unlock_irqrestore(&ide_lock, flags);
@@ -2221,6 +2316,8 @@ void ide_unregister(struct ata_channel *channel)
 	channel->udma_four = old_hwif.udma_four;
 #ifdef CONFIG_BLK_DEV_IDEPCI
 	channel->pci_dev = old_hwif.pci_dev;
+#else
+	channel->pci_dev = NULL;
 #endif
 	channel->straight8 = old_hwif.straight8;
 abort:
@@ -2699,25 +2796,6 @@ static int ide_ioctl (struct inode *inode, struct file *file,
 	}
 }
 
-void ide_teardown_commandlist(ide_drive_t *drive)
-{
-#ifdef CONFIG_BLK_DEV_IDEPCI
-	struct pci_dev *pdev = drive->channel->pci_dev;
-#else
-	struct pci_dev *pdev = NULL;
-#endif
-	struct list_head *entry;
-
-	list_for_each(entry, &drive->free_req) {
-		struct ata_request *ar = list_ata_entry(entry);
-
-		list_del(&ar->ar_queue);
-		kfree(ar->ar_sg_table);
-		pci_free_consistent(pdev, PRD_SEGMENTS * PRD_BYTES, ar->ar_dmatable_cpu, ar->ar_dmatable);
-		kfree(ar);
-	}
-}
-
 int ide_build_commandlist(ide_drive_t *drive)
 {
 #ifdef CONFIG_BLK_DEV_IDEPCI
@@ -2725,24 +2803,26 @@ int ide_build_commandlist(ide_drive_t *drive)
 #else
 	struct pci_dev *pdev = NULL;
 #endif
+	struct list_head *p;
+	unsigned long flags;
 	struct ata_request *ar;
-	ide_tag_info_t *tcq;
-	int i, err;
+	int i, cur;
 
-	tcq = kmalloc(sizeof(ide_tag_info_t), GFP_ATOMIC);
-	if (!tcq)
-		return -ENOMEM;
+	spin_lock_irqsave(&ide_lock, flags);
 
-	drive->tcq = tcq;
-	memset(drive->tcq, 0, sizeof(ide_tag_info_t));
+	cur = 0;
+	list_for_each(p, &drive->free_req)
+		cur++;
 
-	INIT_LIST_HEAD(&drive->free_req);
-	drive->using_tcq = 0;
+	/*
+	 * for now, just don't shrink it...
+	 */
+	if (drive->queue_depth <= cur) {
+		spin_unlock_irqrestore(&ide_lock, flags);
+		return 0;
+	}
 
-	err = -ENOMEM;
-	for (i = 0; i < drive->queue_depth; i++) {
-		/* Having kzmalloc would help reduce code size at quite
-		 * many places in kernel. */
+	for (i = cur; i < drive->queue_depth; i++) {
 		ar = kmalloc(sizeof(*ar), GFP_ATOMIC);
 		if (!ar)
 			break;
@@ -2767,25 +2847,33 @@ int ide_build_commandlist(ide_drive_t *drive)
 		 * pheew, all done, add to list
 		 */
 		list_add_tail(&ar->ar_queue, &drive->free_req);
+		++cur;
 	}
+	drive->queue_depth = cur;
+	spin_unlock_irqrestore(&ide_lock, flags);
+	return 0;
+}
 
-	if (i) {
-		drive->queue_depth = i;
-		if (i >= 1) {
-			drive->tcq->queued = 0;
-			drive->tcq->active_tag = -1;
+int ide_init_commandlist(ide_drive_t *drive)
+{
+	INIT_LIST_HEAD(&drive->free_req);
 
-			return 0;
-		}
+	return ide_build_commandlist(drive);
+}
 
-		kfree(drive->tcq);
-		drive->tcq = NULL;
-		err = 0;
-	}
+void ide_teardown_commandlist(ide_drive_t *drive)
+{
+	struct pci_dev *pdev= drive->channel->pci_dev;
+	struct list_head *entry;
 
-	kfree(drive->tcq);
-	drive->tcq = NULL;
-	return err;
+	list_for_each(entry, &drive->free_req) {
+		struct ata_request *ar = list_ata_entry(entry);
+
+		list_del(&ar->ar_queue);
+		kfree(ar->ar_sg_table);
+		pci_free_consistent(pdev, PRD_SEGMENTS * PRD_BYTES, ar->ar_dmatable_cpu, ar->ar_dmatable);
+		kfree(ar);
+	}
 }
 
 static int ide_check_media_change (kdev_t i_rdev)
@@ -3046,7 +3134,7 @@ int __init ide_setup (char *s)
 		unit = unit % MAX_DRIVES;
 		hwif = &ide_hwifs[hw];
 		drive = &hwif->drives[unit];
-		if (strncmp(s + 4, "ide-", 4) == 0) {
+		if (!strncmp(s + 4, "ide-", 4)) {
 			strncpy(drive->driver_req, s + 4, 9);
 			goto done;
 		}
@@ -3128,7 +3216,7 @@ int __init ide_setup (char *s)
 	/*
 	 * Look for bus speed option:  "idebus="
 	 */
-	if (strncmp(s, "idebus", 6)) {
+	if (!strncmp(s, "idebus", 6)) {
 		if (match_parm(&s[6], NULL, vals, 1) != 1)
 			goto bad_option;
 		if (vals[0] >= 20 && vals[0] <= 66) {

drivers/ide/pdc4030.c

@@ -648,6 +648,12 @@ ide_startstop_t promise_rw_disk (ide_drive_t *drive, struct request *rq, unsigne
 
 	memset(&taskfile, 0, sizeof(struct hd_drive_task_hdr));
 
+	/* The four drives on the two logical (one physical) interfaces
+	   are distinguished by writing the drive number (0-3) to the
+	   Feature register.
+	   FIXME: Is promise_selectproc now redundant??
+	 */
+	taskfile.feature    = (drive->channel->unit << 1) + drive->select.b.unit;
 	taskfile.sector_count	= rq->nr_sectors;
 	taskfile.sector_number	= block;
 	taskfile.low_cylinder	= (block>>=8);

include/linux/ide.h

@@ -273,19 +273,22 @@ typedef union {
 	} b;
 } special_t;
 
-#define IDE_MAX_TAG	32		/* spec says 32 max */
+#define IDE_MAX_TAG		(32)		/* spec says 32 max */
+#define IDE_INACTIVE_TAG	(-1)
 
 struct ata_request;
 typedef struct ide_tag_info_s {
 	unsigned long tag_mask;			/* next tag bit mask */
 	struct ata_request *ar[IDE_MAX_TAG];	/* in-progress requests */
 	int active_tag;				/* current active tag */
+
 	int queued;				/* current depth */
 
 	/*
 	 * stats ->
 	 */
 	int max_depth;				/* max depth ever */
+
 	int max_last_depth;			/* max since last check */
 
 	/*
@@ -295,14 +298,19 @@ typedef struct ide_tag_info_s {
 	 */
 	int immed_rel;
 	int immed_comp;
+	unsigned long oldest_command;
 } ide_tag_info_t;
 
 #define IDE_GET_AR(drive, tag)	((drive)->tcq->ar[(tag)])
 #define IDE_CUR_TAG(drive)	(IDE_GET_AR((drive), (drive)->tcq->active_tag))
-#define IDE_SET_CUR_TAG(drive, tag)	((drive)->tcq->active_tag = (tag))
+#define IDE_SET_CUR_TAG(drive, tag)	\
+	do {						\
+		((drive)->tcq->active_tag = (tag));	\
+		if ((tag) == IDE_INACTIVE_TAG)		\
+			HWGROUP((drive))->rq = NULL;	\
+	} while (0);
 
-#define IDE_CUR_AR(drive)	\
-	((drive)->using_tcq ? IDE_CUR_TAG((drive)) : HWGROUP((drive))->rq->special)
+#define IDE_CUR_AR(drive)	(HWGROUP((drive))->rq->special)
 
 struct ide_settings_s;
 
@@ -359,6 +367,7 @@ typedef struct ide_drive_s {
 	unsigned autotune	: 2;	/* 1=autotune, 2=noautotune, 0=default */
 	unsigned remap_0_to_1	: 2;	/* 0=remap if ezdrive, 1=remap, 2=noremap */
 	unsigned ata_flash	: 1;	/* 1=present, 0=default */
+	unsigned service_pending: 1;
 	unsigned	addressing;	/* : 2; 0=28-bit, 1=48-bit, 2=64-bit */
 	byte		scsi;		/* 0=default, 1=skip current ide-subdriver for ide-scsi emulation */
 	select_t	select;		/* basic drive/head select reg value */
@@ -546,7 +555,7 @@ extern void ide_unregister(struct ata_channel *hwif);
 typedef enum {
 	ide_stopped,	/* no drive operation was started */
 	ide_started,	/* a drive operation was started, and a handler was set */
-	ide_released	/* started and released bus */
+	ide_released,	/* started, handler set, bus released */
 } ide_startstop_t;
 
 /*
@@ -980,6 +989,11 @@ extern void revalidate_drives(void);
 #define ATA_AR_SETUP	2
 #define ATA_AR_RETURN	4
 
+/*
+ * if turn-around time is longer than this, halve queue depth
+ */
+#define ATA_AR_MAX_TURNAROUND	(3 * HZ)
+
 #define list_ata_entry(entry) list_entry((entry), struct ata_request, ar_queue)
 
 static inline void ata_ar_init(ide_drive_t *drive, struct ata_request *ar)
@@ -1026,7 +1040,7 @@ static inline void ata_ar_put(ide_drive_t *drive, struct ata_request *ar)
 	ar->ar_rq = NULL;
 }
 
-extern inline int ide_get_tag(ide_drive_t *drive)
+static inline int ide_get_tag(ide_drive_t *drive)
 {
 	int tag = ffz(drive->tcq->tag_mask);
 
@@ -1043,12 +1057,28 @@ extern inline int ide_get_tag(ide_drive_t *drive)
 }
 
 #ifdef CONFIG_BLK_DEV_IDE_TCQ
-# define ide_pending_commands(drive)	((drive)->using_tcq && (drive)->tcq->queued)
+static inline int ide_pending_commands(ide_drive_t *drive)
+{
+	if (!drive->tcq)
+		return 0;
+
+	return drive->tcq->queued;
+}
+
+static inline int ide_can_queue(ide_drive_t *drive)
+{
+	if (!drive->tcq)
+		return 1;
+
+	return drive->tcq->queued < drive->queue_depth;
+}
 #else
-# define ide_pending_commands(drive)	0
+#define ide_pending_commands(drive)	(0)
+#define ide_can_queue(drive)		(1)
 #endif
 
 int ide_build_commandlist(ide_drive_t *);
+int ide_init_commandlist(ide_drive_t *);
 void ide_teardown_commandlist(ide_drive_t *);
 int ide_tcq_dmaproc(ide_dma_action_t, ide_drive_t *);
 ide_startstop_t ide_start_tag(ide_dma_action_t, ide_drive_t *, struct ata_request *);