2 files changed, 26 insertions, 4 deletions

diff --git a/drivers/scsi/libata-bmdma.c b/drivers/scsi/libata-bmdma.c
index 95d81d86d8b7..835dff0bafdc 100644
--- a/drivers/scsi/libata-bmdma.c
+++ b/drivers/scsi/libata-bmdma.c
@@ -703,6 +703,7 @@ ata_pci_init_native_mode(struct pci_dev *pdev, struct ata_port_info **port, int
         struct ata_probe_ent *probe_ent =
                 ata_probe_ent_alloc(pci_dev_to_dev(pdev), port[0]);
         int p = 0;
+        unsigned long bmdma;
 
         if (!probe_ent)
                 return NULL;
@@ -716,7 +717,12 @@ ata_pci_init_native_mode(struct pci_dev *pdev, struct ata_port_info **port, int
                 probe_ent->port[p].altstatus_addr =
                 probe_ent->port[p].ctl_addr =
                         pci_resource_start(pdev, 1) | ATA_PCI_CTL_OFS;
-                probe_ent->port[p].bmdma_addr = pci_resource_start(pdev, 4);
+                bmdma = pci_resource_start(pdev, 4);
+                if (bmdma) {
+                        if (inb(bmdma + 2) & 0x80)
+                                probe_ent->host_set_flags |= ATA_HOST_SIMPLEX;
+                        probe_ent->port[p].bmdma_addr = bmdma;
+                }
                 ata_std_ports(&probe_ent->port[p]);
                 p++;
         }
@@ -726,7 +732,13 @@ ata_pci_init_native_mode(struct pci_dev *pdev, struct ata_port_info **port, int
                 probe_ent->port[p].altstatus_addr =
                 probe_ent->port[p].ctl_addr =
                         pci_resource_start(pdev, 3) | ATA_PCI_CTL_OFS;
-                probe_ent->port[p].bmdma_addr = pci_resource_start(pdev, 4) + 8;
+                bmdma = pci_resource_start(pdev, 4);
+                if (bmdma) {
+                        bmdma += 8;
+                        if(inb(bmdma + 2) & 0x80)
+                        probe_ent->host_set_flags |= ATA_HOST_SIMPLEX;
+                        probe_ent->port[p].bmdma_addr = bmdma;
+                }
                 ata_std_ports(&probe_ent->port[p]);
                 p++;
         }
@@ -740,6 +752,7 @@ static struct ata_probe_ent *ata_pci_init_legacy_port(struct pci_dev *pdev,
                                 struct ata_port_info *port, int port_num)
 {
         struct ata_probe_ent *probe_ent;
+        unsigned long bmdma;
 
         probe_ent = ata_probe_ent_alloc(pci_dev_to_dev(pdev), port);
         if (!probe_ent)
@@ -766,8 +779,13 @@ static struct ata_probe_ent *ata_pci_init_legacy_port(struct pci_dev *pdev,
                         break;
         }
 
-        probe_ent->port[0].bmdma_addr =
-                pci_resource_start(pdev, 4) + 8 * port_num;
+        bmdma = pci_resource_start(pdev, 4);
+        if (bmdma != 0) {
+                bmdma += 8 * port_num;
+                probe_ent->port[0].bmdma_addr = bmdma;
+                if (inb(bmdma + 2) & 0x80)
+                        probe_ent->host_set_flags |= ATA_HOST_SIMPLEX;
+        }
         ata_std_ports(&probe_ent->port[0]);
 
         return probe_ent;
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 9fcc061e3adf..a5c213ce97c9 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -160,6 +160,9 @@ enum {
         ATA_QCFLAG_DMAMAP       = ATA_QCFLAG_SG | ATA_QCFLAG_SINGLE,
         ATA_QCFLAG_EH_SCHEDULED = (1 << 5), /* EH scheduled */
 
+        /* host set flags */
+        ATA_HOST_SIMPLEX        = (1 << 0),     /* Host is simplex, one DMA channel per host_set only */
+        
         /* various lengths of time */
         ATA_TMOUT_PIO           = 30 * HZ,
         ATA_TMOUT_BOOT          = 30 * HZ,      /* heuristic */
@@ -278,6 +281,7 @@ struct ata_probe_ent {
         unsigned long           irq;
         unsigned int            irq_flags;
         unsigned long           host_flags;
+        unsigned long           host_set_flags;
         void __iomem            *mmio_base;
         void                    *private_data;
 };