libata: implement libata.force module parameter

This patch implements libata.force module parameter which can
selectively override ATA port, link and device configurations
including cable type, SATA PHY SPD limit, transfer mode and NCQ.

For example, you can say "use 1.5Gbps for all fan-out ports attached
to the second port but allow 3.0Gbps for the PMP device itself, oh,
the device attached to the third fan-out port chokes on NCQ and
shouldn't go over UDMA4" by the following.

 libata.force=2:1.5g,2.15:3.0g,2.03:noncq,udma4

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

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 4e31071acc0..698ce2cea52 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -2393,9 +2393,11 @@ static int ata_eh_revalidate_and_attach(struct ata_link *link,
         }
 
         /* PDIAG- should have been released, ask cable type if post-reset */
-        if (ata_is_host_link(link) && ap->ops->cable_detect &&
-            (ehc->i.flags & ATA_EHI_DID_RESET))
-                ap->cbl = ap->ops->cable_detect(ap);
+        if ((ehc->i.flags & ATA_EHI_DID_RESET) && ata_is_host_link(link)) {
+                if (ap->ops->cable_detect)
+                        ap->cbl = ap->ops->cable_detect(ap);
+                ata_force_cbl(ap);
+        }
 
         /* Configure new devices forward such that user doesn't see
          * device detection messages backwards.