libata,pata_via: revert ata_wait_idle() removal from ata_sff/via_tf_load()

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>

drivers/ata/libata-sff.c

@@ -418,6 +418,7 @@ void ata_sff_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
 		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)) {
@@ -453,6 +454,8 @@ void ata_sff_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
 		iowrite8(tf->device, ioaddr->device_addr);
 		VPRINTK("device 0x%X\n", tf->device);
 	}
+
+	ata_wait_idle(ap);
 }
 EXPORT_SYMBOL_GPL(ata_sff_tf_load);
 

drivers/ata/pata_via.c

@@ -417,6 +417,8 @@ static void via_tf_load(struct ata_port *ap, const struct ata_taskfile *tf)
 			tf->lbam,
 			tf->lbah);
 	}
+
+	ata_wait_idle(ap);
 }
 
 static int via_port_start(struct ata_port *ap)