[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>

diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 38fc75d..4e6c2e8 100644 (file)
--- 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)