libata: Keep shadow last_ctl up to date during resets

libata keeps a shadow copy of the ATA CTL register (which is write only),
and only writes to the hardware when the required value doesn't match
the shadow. However this copy wasn't being maintained when performing
reset functions. This could cause problems for the first operation after
a reset when the correct value might not be written to the CTL register.

This problem was observed when hotplugging a drive: the identify command
was being issued with interrupts enabled, when they should have been
disabled.
Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-sff.c

@@ -2066,6 +2066,7 @@ static int ata_bus_softreset(struct ata_port *ap, unsigned int devmask,
 	iowrite8(ap->ctl | ATA_SRST, ioaddr->ctl_addr);
 	udelay(20);	/* FIXME: flush */
 	iowrite8(ap->ctl, ioaddr->ctl_addr);
+	ap->last_ctl = ap->ctl;
 
 	/* wait the port to become ready */
 	return ata_sff_wait_after_reset(&ap->link, devmask, deadline);
@@ -2190,8 +2191,10 @@ void ata_sff_postreset(struct ata_link *link, unsigned int *classes)
 	}
 
 	/* set up device control */
-	if (ap->ioaddr.ctl_addr)
+	if (ap->ioaddr.ctl_addr) {
 		iowrite8(ap->ctl, ap->ioaddr.ctl_addr);
+		ap->last_ctl = ap->ctl;
+	}
 }
 EXPORT_SYMBOL_GPL(ata_sff_postreset);
 
@@ -2534,6 +2537,7 @@ void ata_bus_reset(struct ata_port *ap)
 	if (ap->flags & (ATA_FLAG_SATA_RESET | ATA_FLAG_SRST)) {
 		/* set up device control for ATA_FLAG_SATA_RESET */
 		iowrite8(ap->ctl, ioaddr->ctl_addr);
+		ap->last_ctl = ap->ctl;
 	}
 
 	DPRINTK("EXIT\n");