1 files changed, 27 insertions, 2 deletions

diff --git a/drivers/ata/pata_sc1200.c b/drivers/ata/pata_sc1200.c
index 36a0c3593297..f49814d6fd2e 100644
--- a/drivers/ata/pata_sc1200.c
+++ b/drivers/ata/pata_sc1200.c
@@ -2,7 +2,6 @@
  * New ATA layer SC1200 driver          Alan Cox <alan@lxorguk.ukuu.org.uk>
  *
  * TODO: Mode selection filtering
- * TODO: Can't enable second channel until ATA core has serialize
  * TODO: Needs custom DMA cleanup code
  *
  * Based very heavily on
@@ -178,6 +177,31 @@ static unsigned int sc1200_qc_issue(struct ata_queued_cmd *qc)
         return ata_sff_qc_issue(qc);
 }
 
+/**
+ *      sc1200_qc_defer -       implement serialization
+ *      @qc: command
+ *
+ *      Serialize command issue on this controller.
+ */
+
+static int sc1200_qc_defer(struct ata_queued_cmd *qc)
+{
+        struct ata_host *host = qc->ap->host;
+        struct ata_port *alt = host->ports[1 ^ qc->ap->port_no];
+        int rc;
+
+        /* First apply the usual rules */
+        rc = ata_std_qc_defer(qc);
+        if (rc != 0)
+                return rc;
+
+        /* Now apply serialization rules. Only allow a command if the
+           other channel state machine is idle */
+        if (alt && alt->qc_active)
+                return  ATA_DEFER_PORT;
+        return 0;
+}
+
 static struct scsi_host_template sc1200_sht = {
         ATA_BMDMA_SHT(DRV_NAME),
         .sg_tablesize   = LIBATA_DUMB_MAX_PRD,
@@ -187,6 +211,7 @@ static struct ata_port_operations sc1200_port_ops = {
         .inherits       = &ata_bmdma_port_ops,
         .qc_prep        = ata_sff_dumb_qc_prep,
         .qc_issue       = sc1200_qc_issue,
+        .qc_defer       = sc1200_qc_defer,
         .cable_detect   = ata_cable_40wire,
         .set_piomode    = sc1200_set_piomode,
         .set_dmamode    = sc1200_set_dmamode,
@@ -211,7 +236,7 @@ static int sc1200_init_one(struct pci_dev *dev, const struct pci_device_id *id)
                 .port_ops = &sc1200_port_ops
         };
         /* Can't enable port 2 yet, see top comments */
-        const struct ata_port_info *ppi[] = { &info, &ata_dummy_port_info };
+        const struct ata_port_info *ppi[] = { &info, };
 
         return ata_pci_sff_init_one(dev, ppi, &sc1200_sht, NULL);
 }