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>

2 files changed, 37 insertions, 37 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;
 }
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 7b61562cdd40..1abfdba8d99b 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -1964,8 +1964,7 @@ static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
 {
         struct ata_eh_context *ehc = &ap->eh_context;
         struct ata_device *dev;
-        int down_xfermask, i, rc;
-        int dnxfer_sel;
+        int i, rc;
 
         DPRINTK("ENTER\n");
 
@@ -1994,7 +1993,6 @@ static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
         }
 
  retry:
-        down_xfermask = 0;
         rc = 0;
 
         /* if UNLOADING, finish immediately */
@@ -2039,10 +2037,8 @@ static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
         /* configure transfer mode if necessary */
         if (ehc->i.flags & ATA_EHI_SETMODE) {
                 rc = ata_set_mode(ap, &dev);
-                if (rc) {
-                        down_xfermask = 1;
+                if (rc)
                         goto dev_fail;
-                }
                 ehc->i.flags &= ~ATA_EHI_SETMODE;
         }
 
@@ -2054,22 +2050,27 @@ static int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
         goto out;
 
  dev_fail:
+        ehc->tries[dev->devno]--;
+
         switch (rc) {
-        case -ENODEV:
-                /* device missing, schedule probing */
-                ehc->i.probe_mask |= (1 << dev->devno);
         case -EINVAL:
+                /* eeek, something went very wrong, give up */
                 ehc->tries[dev->devno] = 0;
                 break;
+
+        case -ENODEV:
+                /* device missing or wrong IDENTIFY data, schedule probing */
+                ehc->i.probe_mask |= (1 << dev->devno);
+                /* give it just one more chance */
+                ehc->tries[dev->devno] = min(ehc->tries[dev->devno], 1);
         case -EIO:
-                sata_down_spd_limit(ap);
-        default:
-                ehc->tries[dev->devno]--;
-                dnxfer_sel = ATA_DNXFER_ANY;
-                if (ehc->tries[dev->devno] == 1)
-                        dnxfer_sel = ATA_DNXFER_FORCE_PIO0;
-                if (down_xfermask && ata_down_xfermask_limit(dev, dnxfer_sel))
-                        ehc->tries[dev->devno] = 0;
+                if (ehc->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 (ata_dev_enabled(dev) && !ehc->tries[dev->devno]) {