pata_sl82c105: dual channel support

Use qc_defer to serialize the two channels

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 31 insertions, 2 deletions

diff --git a/drivers/ata/pata_sl82c105.c b/drivers/ata/pata_sl82c105.c
index 1388cef52c07..81ef207f8265 100644
--- a/drivers/ata/pata_sl82c105.c
+++ b/drivers/ata/pata_sl82c105.c
@@ -26,7 +26,7 @@
 #include <linux/libata.h>
 
 #define DRV_NAME "pata_sl82c105"
-#define DRV_VERSION "0.3.2"
+#define DRV_VERSION "0.3.3"
 
 enum {
         /*
@@ -206,6 +206,34 @@ static void sl82c105_bmdma_stop(struct ata_queued_cmd *qc)
         sl82c105_set_piomode(ap, qc->dev);
 }
 
+/**
+ *      sl82c105_qc_defer       -       implement serialization
+ *      @qc: command
+ *
+ *      We must issue one command per host not per channel because
+ *      of the reset bug.
+ *
+ *      Q: is the scsi host lock sufficient ?
+ */
+
+static int sl82c105_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 sl82c105_sht = {
         .module                 = THIS_MODULE,
         .name                   = DRV_NAME,
@@ -245,6 +273,7 @@ static struct ata_port_operations sl82c105_port_ops = {
         .bmdma_stop     = sl82c105_bmdma_stop,
         .bmdma_status   = ata_bmdma_status,
 
+        .qc_defer       = sl82c105_qc_defer,
         .qc_prep        = ata_qc_prep,
         .qc_issue       = ata_qc_issue_prot,
 
@@ -312,7 +341,7 @@ static int sl82c105_init_one(struct pci_dev *dev, const struct pci_device_id *id
         };
         /* for now use only the first port */
         const struct ata_port_info *ppi[] = { &info_early,
-                                               &ata_dummy_port_info };
+                                               NULL };
         u32 val;
         int rev;