[PATCH] ata_piix: fix ghost device probing by honoring PCS present bits

Move out PCS handling from piix_sata_prereset() into
piix_sata_present_mask() and use it from newly implemented
piix_sata_softreset().  Class codes for devices which are indicated to
be absent by PCS are cleared to ATA_DEV_NONE.  This fixes ghost device
problem reported on ICH6 and 7.

This patch moves PCS handling from prereset to softreset, which makes
two behavior changes.

* perform softreset even when PCS indicates no device
* PCS handling is repeated before retrying softresets due to reset
  failures.

Both behavior changes are intended and more consistent with how other
drivers behave.

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

1 files changed, 43 insertions, 17 deletions

diff --git a/drivers/scsi/ata_piix.c b/drivers/scsi/ata_piix.c
index 5e8afc876980..01b3530cf6df 100644
--- a/drivers/scsi/ata_piix.c
+++ b/drivers/scsi/ata_piix.c
@@ -531,27 +531,25 @@ static void piix_pata_error_handler(struct ata_port *ap)
 }
 
 /**
- *      piix_sata_prereset - prereset for SATA host controller
+ *      piix_sata_present_mask - determine present mask for SATA host controller
  *      @ap: Target port
  *
- *      Reads and configures SATA PCI device's PCI config register
- *      Port Configuration and Status (PCS) to determine port and
- *      device availability.  Return -ENODEV to skip reset if no
- *      device is present.
+ *      Reads SATA PCI device's PCI config register Port Configuration
+ *      and Status (PCS) to determine port and device availability.
  *
  *      LOCKING:
  *      None (inherited from caller).
  *
  *      RETURNS:
- *      0 if device is present, -ENODEV otherwise.
+ *      determined present_mask
  */
-static int piix_sata_prereset(struct ata_port *ap)
+static unsigned int piix_sata_present_mask(struct ata_port *ap)
 {
         struct pci_dev *pdev = to_pci_dev(ap->host_set->dev);
         struct piix_host_priv *hpriv = ap->host_set->private_data;
         const unsigned int *map = hpriv->map;
         int base = 2 * ap->hard_port_no;
-        unsigned int present = 0;
+        unsigned int present_mask = 0;
         int port, i;
         u16 pcs;
 
@@ -564,24 +562,52 @@ static int piix_sata_prereset(struct ata_port *ap)
                         continue;
                 if ((ap->flags & PIIX_FLAG_IGNORE_PCS) ||
                     (pcs & 1 << (hpriv->map_db->present_shift + port)))
-                        present = 1;
+                        present_mask |= 1 << i;
         }
 
-        DPRINTK("ata%u: LEAVE, pcs=0x%x present=0x%x\n",
-                ap->id, pcs, present);
+        DPRINTK("ata%u: LEAVE, pcs=0x%x present_mask=0x%x\n",
+                ap->id, pcs, present_mask);
 
-        if (!present) {
-                ata_port_printk(ap, KERN_INFO, "SATA port has no device.\n");
-                ap->eh_context.i.action &= ~ATA_EH_RESET_MASK;
-                return 0;
+        return present_mask;
+}
+
+/**
+ *      piix_sata_softreset - reset SATA host port via ATA SRST
+ *      @ap: port to reset
+ *      @classes: resulting classes of attached devices
+ *
+ *      Reset SATA host port via ATA SRST.  On controllers with
+ *      reliable PCS present bits, the bits are used to determine
+ *      device presence.
+ *
+ *      LOCKING:
+ *      Kernel thread context (may sleep)
+ *
+ *      RETURNS:
+ *      0 on success, -errno otherwise.
+ */
+static int piix_sata_softreset(struct ata_port *ap, unsigned int *classes)
+{
+        unsigned int present_mask;
+        int i, rc;
+
+        present_mask = piix_sata_present_mask(ap);
+
+        rc = ata_std_softreset(ap, classes);
+        if (rc)
+                return rc;
+
+        for (i = 0; i < ATA_MAX_DEVICES; i++) {
+                if (!(present_mask & (1 << i)))
+                        classes[i] = ATA_DEV_NONE;
         }
 
-        return ata_std_prereset(ap);
+        return 0;
 }
 
 static void piix_sata_error_handler(struct ata_port *ap)
 {
-        ata_bmdma_drive_eh(ap, piix_sata_prereset, ata_std_softreset, NULL,
+        ata_bmdma_drive_eh(ap, ata_std_prereset, piix_sata_softreset, NULL,
                            ata_std_postreset);
 }