libata: improve probe failure handling

* Move forcing device to PIO0 on device disable into
  ata_dev_disable().  This makes both old and new EHs act the same
  way.

* Speed down only PIO mode on probe failure.  All commands used during
  probing are PIO commands.  There's no point in speeding down DMA.

* Retry at least once after -ENODEV.  Some devices report garbled
  IDENTIFY data after certain events.  This shouldn't cause device
  detach and re-attach.

* Rearrange EH failure path for simplicity.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 19 insertions, 20 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 249d487c091e..24c6505f062d 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -600,6 +600,8 @@ void ata_dev_disable(struct ata_device *dev)
 {
         if (ata_dev_enabled(dev) && ata_msg_drv(dev->ap)) {
                 ata_dev_printk(dev, KERN_WARNING, "disabled\n");
+                ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO0 |
+                                             ATA_DNXFER_QUIET);
                 dev->class++;
         }
 }
@@ -1778,9 +1780,8 @@ int ata_bus_probe(struct ata_port *ap)
 {
         unsigned int classes[ATA_MAX_DEVICES];
         int tries[ATA_MAX_DEVICES];
-        int i, rc, down_xfermask;
+        int i, rc;
         struct ata_device *dev;
-        int dnxfer_sel;
 
         ata_port_probe(ap);
 
@@ -1788,8 +1789,6 @@ int ata_bus_probe(struct ata_port *ap)
                 tries[i] = ATA_PROBE_MAX_TRIES;
 
  retry:
-        down_xfermask = 0;
-
         /* reset and determine device classes */
         ap->ops->phy_reset(ap);
 
@@ -1837,10 +1836,8 @@ int ata_bus_probe(struct ata_port *ap)
 
         /* configure transfer mode */
         rc = ata_set_mode(ap, &dev);
-        if (rc) {
-                down_xfermask = 1;
+        if (rc)
                 goto fail;
-        }
 
         for (i = 0; i < ATA_MAX_DEVICES; i++)
                 if (ata_dev_enabled(&ap->device[i]))
@@ -1852,27 +1849,29 @@ int ata_bus_probe(struct ata_port *ap)
         return -ENODEV;
 
  fail:
+        tries[dev->devno]--;
+
         switch (rc) {
         case -EINVAL:
-        case -ENODEV:
+                /* eeek, something went very wrong, give up */
                 tries[dev->devno] = 0;
                 break;
+
+        case -ENODEV:
+                /* give it just one more chance */
+                tries[dev->devno] = min(tries[dev->devno], 1);
         case -EIO:
-                sata_down_spd_limit(ap);
-                /* fall through */
-        default:
-                tries[dev->devno]--;
-                dnxfer_sel = ATA_DNXFER_ANY;
-                if (tries[dev->devno] == 1)
-                        dnxfer_sel = ATA_DNXFER_FORCE_PIO0;
-                if (down_xfermask && ata_down_xfermask_limit(dev, dnxfer_sel))
-                        tries[dev->devno] = 0;
+                if (tries[dev->devno] == 1) {
+                        /* This is the last chance, better to slow
+                         * down than lose it.
+                         */
+                        sata_down_spd_limit(ap);
+                        ata_down_xfermask_limit(dev, ATA_DNXFER_PIO);
+                }
         }
 
-        if (!tries[dev->devno]) {
-                ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO0);
+        if (!tries[dev->devno])
                 ata_dev_disable(dev);
-        }
 
         goto retry;
 }