3 files changed, 31 insertions, 8 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index bf8d3b8c171d..85283c04d642 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -6826,6 +6826,7 @@ EXPORT_SYMBOL_GPL(ata_check_status);
 EXPORT_SYMBOL_GPL(ata_altstatus);
 EXPORT_SYMBOL_GPL(ata_exec_command);
 EXPORT_SYMBOL_GPL(ata_port_start);
+EXPORT_SYMBOL_GPL(ata_sff_port_start);
 EXPORT_SYMBOL_GPL(ata_interrupt);
 EXPORT_SYMBOL_GPL(ata_do_set_mode);
 EXPORT_SYMBOL_GPL(ata_data_xfer);
diff --git a/drivers/ata/libata-sff.c b/drivers/ata/libata-sff.c
index e35d13466c69..ce84805ba5f1 100644
--- a/drivers/ata/libata-sff.c
+++ b/drivers/ata/libata-sff.c
@@ -80,25 +80,25 @@ u8 ata_dummy_irq_on (struct ata_port *ap) 	{ return 0; }
 u8 ata_irq_ack(struct ata_port *ap, unsigned int chk_drq)
 {
         unsigned int bits = chk_drq ? ATA_BUSY | ATA_DRQ : ATA_BUSY;
-        u8 host_stat, post_stat, status;
+        u8 host_stat = 0, post_stat = 0, status;
 
         status = ata_busy_wait(ap, bits, 1000);
         if (status & bits)
                 if (ata_msg_err(ap))
                         printk(KERN_ERR "abnormal status 0x%X\n", status);
 
-        /* get controller status; clear intr, err bits */
-        host_stat = ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
-        iowrite8(host_stat | ATA_DMA_INTR | ATA_DMA_ERR,
-                 ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
-
-        post_stat = ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
+        if (ap->ioaddr.bmdma_addr) {
+                /* get controller status; clear intr, err bits */
+                host_stat = ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
+                iowrite8(host_stat | ATA_DMA_INTR | ATA_DMA_ERR,
+                         ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
 
+                post_stat = ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
+        }
         if (ata_msg_intr(ap))
                 printk(KERN_INFO "%s: irq ack: host_stat 0x%X, new host_stat 0x%X, drv_stat 0x%X\n",
                         __FUNCTION__,
                         host_stat, post_stat, status);
-
         return status;
 }
 
@@ -516,6 +516,27 @@ void ata_bmdma_post_internal_cmd(struct ata_queued_cmd *qc)
                 ata_bmdma_stop(qc);
 }
 
+/**
+ *      ata_sff_port_start - Set port up for dma.
+ *      @ap: Port to initialize
+ *
+ *      Called just after data structures for each port are
+ *      initialized.  Allocates space for PRD table if the device
+ *      is DMA capable SFF.
+ *
+ *      May be used as the port_start() entry in ata_port_operations.
+ *
+ *      LOCKING:
+ *      Inherited from caller.
+ */
+
+int ata_sff_port_start(struct ata_port *ap)
+{
+        if (ap->ioaddr.bmdma_addr)
+                return ata_port_start(ap);
+        return 0;
+}
+
 #ifdef CONFIG_PCI
 
 static int ata_resources_present(struct pci_dev *pdev, int port)
diff --git a/include/linux/libata.h b/include/linux/libata.h
index a6a3113120a4..745c4f9b4caa 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -753,6 +753,7 @@ extern u8 ata_check_status(struct ata_port *ap);
 extern u8 ata_altstatus(struct ata_port *ap);
 extern void ata_exec_command(struct ata_port *ap, const struct ata_taskfile *tf);
 extern int ata_port_start (struct ata_port *ap);
+extern int ata_sff_port_start (struct ata_port *ap);
 extern irqreturn_t ata_interrupt (int irq, void *dev_instance);
 extern void ata_data_xfer(struct ata_device *adev, unsigned char *buf,
                           unsigned int buflen, int write_data);