libata: isolate and rework cable logic

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 44 insertions, 4 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 54f85508bc6e..9121cc443be8 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -3886,6 +3886,49 @@ static int ata_is_40wire(struct ata_device *dev)
 }
 
 /**
+ *      cable_is_40wire         -       40/80/SATA decider
+ *      @ap: port to consider
+ *
+ *      This function encapsulates the policy for speed management
+ *      in one place. At the moment we don't cache the result but
+ *      there is a good case for setting ap->cbl to the result when
+ *      we are called with unknown cables (and figuring out if it
+ *      impacts hotplug at all).
+ *
+ *      Return 1 if the cable appears to be 40 wire.
+ */
+
+static int cable_is_40wire(struct ata_port *ap)
+{
+        struct ata_link *link;
+        struct ata_device *dev;
+
+        /* If the controller thinks we are 40 wire, we are */
+        if (ap->cbl == ATA_CBL_PATA40)
+                return 1;
+        /* If the controller thinks we are 80 wire, we are */
+        if (ap->cbl == ATA_CBL_PATA80 || ap->cbl == ATA_CBL_SATA)
+                return 0;
+        /* If the controller doesn't know we scan
+
+           - Note: We look for all 40 wire detects at this point.
+             Any 80 wire detect is taken to be 80 wire cable
+             because
+             - In many setups only the one drive (slave if present)
+               will give a valid detect
+             - If you have a non detect capable drive you don't
+               want it to colour the choice
+        */
+        ata_port_for_each_link(link, ap) {
+                ata_link_for_each_dev(dev, link) {
+                        if (!ata_is_40wire(dev))
+                                return 0;
+                }
+        }
+        return 1;
+}
+
+/**
  *      ata_dev_xfermask - Compute supported xfermask of the given device
  *      @dev: Device to compute xfermask for
  *
@@ -3953,10 +3996,7 @@ static void ata_dev_xfermask(struct ata_device *dev)
          */
         if (xfer_mask & (0xF8 << ATA_SHIFT_UDMA))
                 /* UDMA/44 or higher would be available */
-                if ((ap->cbl == ATA_CBL_PATA40) ||
-                    (ata_is_40wire(dev) &&
-                    (ap->cbl == ATA_CBL_PATA_UNK ||
-                     ap->cbl == ATA_CBL_PATA80))) {
+                if (cable_is_40wire(ap)) {
                         ata_dev_printk(dev, KERN_WARNING,
                                  "limited to UDMA/33 due to 40-wire cable\n");
                         xfer_mask &= ~(0xF8 << ATA_SHIFT_UDMA);