[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>

diff --git a/drivers/scsi/ata_piix.c b/drivers/scsi/ata_piix.c
index 5e8afc8..01b3530 100644 (file)
--- 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);
 }