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>

1 files changed, 19 insertions, 13 deletions

diff --git a/drivers/ide/ide-probe.c b/drivers/ide/ide-probe.c
index 56fb0b843429..ee848c705995 100644
--- a/drivers/ide/ide-probe.c
+++ b/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;
 }