Commit 
978c0666 (libata: Remove excess delay in the tf_load path)
removed ata_wait_idle() from ata_sff_tf_load() and via_tf_load().
This caused obscure detection problems in sata_sil.
  https://bugzilla.kernel.org/show_bug.cgi?id=16606
The commit was pure performance optimization.  Revert it for now.
Reported-by: Dieter Plaetinck <dieter@plaetinck.be>
Reported-by: Jan Beulich <JBeulich@novell.com>
Bisected-by: gianluca <gianluca@sottospazio.it>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
                if (ioaddr->ctl_addr)
                        iowrite8(tf->ctl, ioaddr->ctl_addr);
                ap->last_ctl = tf->ctl;
+               ata_wait_idle(ap);
        }
 
        if (is_addr && (tf->flags & ATA_TFLAG_LBA48)) {
                iowrite8(tf->device, ioaddr->device_addr);
                VPRINTK("device 0x%X\n", tf->device);
        }
+
+       ata_wait_idle(ap);
 }
 EXPORT_SYMBOL_GPL(ata_sff_tf_load);
 
 
                        tf->lbam,
                        tf->lbah);
        }
+
+       ata_wait_idle(ap);
 }
 
 static int via_port_start(struct ata_port *ap)