libata: update ->data_xfer hook for ATAPI

Depending on how many bytes are transferred as a unit, PIO data
transfer may consume more bytes than requested.  Knowing how much
data is consumed is necessary to determine how much is left for
draining.  This patch update ->data_xfer such that it returns the
number of consumed bytes.

While at it, it also makes the following changes.

* s/adev/dev/
* use READ/WRITE constants for rw indication
* misc clean ups

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 17 insertions, 13 deletions

diff --git a/drivers/ata/pata_qdi.c b/drivers/ata/pata_qdi.c
index a4c0e502cb42..9f308ed76cc8 100644
--- a/drivers/ata/pata_qdi.c
+++ b/drivers/ata/pata_qdi.c
@@ -124,29 +124,33 @@ static unsigned int qdi_qc_issue_prot(struct ata_queued_cmd *qc)
         return ata_qc_issue_prot(qc);
 }
 
-static void qdi_data_xfer(struct ata_device *adev, unsigned char *buf, unsigned int buflen, int write_data)
+static unsigned int qdi_data_xfer(struct ata_device *dev, unsigned char *buf,
+                                  unsigned int buflen, int rw)
 {
-        struct ata_port *ap = adev->link->ap;
-        int slop = buflen & 3;
+        if (ata_id_has_dword_io(dev->id)) {
+                struct ata_port *ap = dev->link->ap;
+                int slop = buflen & 3;
 
-        if (ata_id_has_dword_io(adev->id)) {
-                if (write_data)
-                        iowrite32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
-                else
+                if (rw == READ)
                         ioread32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
+                else
+                        iowrite32_rep(ap->ioaddr.data_addr, buf, buflen >> 2);
 
                 if (unlikely(slop)) {
-                        __le32 pad = 0;
-                        if (write_data) {
-                                memcpy(&pad, buf + buflen - slop, slop);
-                                iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
-                        } else {
+                        u32 pad;
+                        if (rw == READ) {
                                 pad = cpu_to_le32(ioread32(ap->ioaddr.data_addr));
                                 memcpy(buf + buflen - slop, &pad, slop);
+                        } else {
+                                memcpy(&pad, buf + buflen - slop, slop);
+                                iowrite32(le32_to_cpu(pad), ap->ioaddr.data_addr);
                         }
+                        buflen += 4 - slop;
                 }
         } else
-                ata_data_xfer(adev, buf, buflen, write_data);
+                buflen = ata_data_xfer(dev, buf, buflen, rw);
+
+        return buflen;
 }
 
 static struct scsi_host_template qdi_sht = {