[PATCH] libata: implement per-dev xfermask

Implement per-dev xfermask.  libata used to determine xfermask
per-port - the fastest mode of the slowest device on the port.  This
patch enables per-dev xfermask.

Original patch is from Alan Cox <alan@redhat.com>.  The following
changes are made by me.

* simplex warning message is added
* remove disabled device handling code which is never invoked
  (originally for choosing port-wide lowest PIO mode)

Cc: Alan Cox <alan@redhat.com>
Signed-off-by: Tejun Heo <htejun@gmail.com>

1 files changed, 11 insertions, 29 deletions

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 38fc75d6b39c..4e6c2e8ac0f6 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -3040,10 +3040,6 @@ static int ata_dma_blacklisted(const struct ata_device *dev)
  *      known limits including host controller limits, device
  *      blacklist, etc...
  *
- *      FIXME: The current implementation limits all transfer modes to
- *      the fastest of the lowested device on the port.  This is not
- *      required on most controllers.
- *
  *      LOCKING:
  *      None.
  */
@@ -3052,8 +3048,8 @@ static void ata_dev_xfermask(struct ata_device *dev)
         struct ata_port *ap = dev->ap;
         struct ata_host_set *hs = ap->host_set;
         unsigned long xfer_mask;
-        int i;
 
+        /* controller modes available */
         xfer_mask = ata_pack_xfermask(ap->pio_mask,
                                       ap->mwdma_mask, ap->udma_mask);
 
@@ -3063,34 +3059,20 @@ static void ata_dev_xfermask(struct ata_device *dev)
         if (ap->cbl == ATA_CBL_PATA40)
                 xfer_mask &= ~(0xF8 << ATA_SHIFT_UDMA);
 
-        /* FIXME: Use port-wide xfermask for now */
-        for (i = 0; i < ATA_MAX_DEVICES; i++) {
-                struct ata_device *d = &ap->device[i];
-
-                if (ata_dev_absent(d))
-                        continue;
+        xfer_mask &= ata_pack_xfermask(dev->pio_mask,
+                                       dev->mwdma_mask, dev->udma_mask);
+        xfer_mask &= ata_id_xfermask(dev->id);
 
-                if (ata_dev_disabled(d)) {
-                        /* to avoid violating device selection timing */
-                        xfer_mask &= ata_pack_xfermask(d->pio_mask,
-                                                       UINT_MAX, UINT_MAX);
-                        continue;
-                }
-
-                xfer_mask &= ata_pack_xfermask(d->pio_mask,
-                                               d->mwdma_mask, d->udma_mask);
-                xfer_mask &= ata_id_xfermask(d->id);
-                if (ata_dma_blacklisted(d))
-                        xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
-        }
-
-        if (ata_dma_blacklisted(dev))
+        if (ata_dma_blacklisted(dev)) {
+                xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
                 ata_dev_printk(dev, KERN_WARNING,
                                "device is on DMA blacklist, disabling DMA\n");
+        }
 
-        if (hs->flags & ATA_HOST_SIMPLEX) {
-                if (hs->simplex_claimed)
-                        xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
+        if ((hs->flags & ATA_HOST_SIMPLEX) && hs->simplex_claimed) {
+                xfer_mask &= ~(ATA_MASK_MWDMA | ATA_MASK_UDMA);
+                ata_dev_printk(dev, KERN_WARNING, "simplex DMA is claimed by "
+                               "other device, disabling DMA\n");
         }
 
         if (ap->ops->mode_filter)