ide: skip ide_wait_not_busy() on noprobe-disks

There is a problem in some hardware where the kernel will stall for
35 seconds waiting for disks that don't exist. This patch will skip
waiting for the BSY-bit on IDE drives to go away if you set "hdx=noprobe"
as a kernel option and the disk is not marked as 'present' (like when
you set the geometry by hand).

If no noprobe-option is set the code will work (more or less) as the
original but if set the code will skip the ide_wait_not_busy() for
that drive. Even if there would be a drive there and it is still busy
afterwards it should not matter since it isn't probed for later.

The code also honors the MAX_DRIVES variable instead of assuming that
there will be two harddrives on the bus.

Bart: minor cleanups
Signed-off-by: Jonas Stare <jonas.stare@purplescout.se>
CC: Andrew Morton <akpm@linux-foundation.org>,
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/ide-probe.c

@@ -644,7 +644,7 @@ static void hwif_register (ide_hwif_t *hwif)
 
 static int wait_hwif_ready(ide_hwif_t *hwif)
 {
-	int rc;
+	int unit, rc;
 
 	printk(KERN_DEBUG "Probing IDE interface %s...\n", hwif->name);
 
@@ -661,20 +661,26 @@ static int wait_hwif_ready(ide_hwif_t *hwif)
 		return rc;
 
 	/* Now make sure both master & slave are ready */
-	SELECT_DRIVE(&hwif->drives[0]);
-	hwif->OUTB(8, hwif->io_ports[IDE_CONTROL_OFFSET]);
-	mdelay(2);
-	rc = ide_wait_not_busy(hwif, 35000);
-	if (rc)
-		return rc;
-	SELECT_DRIVE(&hwif->drives[1]);
-	hwif->OUTB(8, hwif->io_ports[IDE_CONTROL_OFFSET]);
-	mdelay(2);
-	rc = ide_wait_not_busy(hwif, 35000);
+	for (unit = 0; unit < MAX_DRIVES; unit++) {
+		ide_drive_t *drive = &hwif->drives[unit];
 
+		/* Ignore disks that we will not probe for later. */
+		if (!drive->noprobe || drive->present) {
+			SELECT_DRIVE(drive);
+			hwif->OUTB(8, hwif->io_ports[IDE_CONTROL_OFFSET]);
+			mdelay(2);
+			rc = ide_wait_not_busy(hwif, 35000);
+			if (rc)
+				goto out;
+		} else
+			printk(KERN_DEBUG "%s: ide_wait_not_busy() skipped\n",
+					  drive->name);
+	}
+out:
 	/* Exit function with master reselected (let's be sane) */
-	SELECT_DRIVE(&hwif->drives[0]);
-	
+	if (unit)
+		SELECT_DRIVE(&hwif->drives[0]);
+
 	return rc;
 }