libata-sff: Fix controllers with no ctl port

Currently, ata_sff_softreset is skipped for controllers with no ctl port.
But that also skips ata_sff_dev_classify required for device detection.
This means that libata is currently broken on controllers with no ctl port.

No device connected:
[    1.872480] pata_isapnp 01:01.02: activated
[    1.889823] scsi2 : pata_isapnp
[    1.890109] ata3: PATA max PIO0 cmd 0x1e8 ctl 0x0 irq 11
[    6.888110] ata3.01: qc timeout (cmd 0xec)
[    6.888179] ata3.01: failed to IDENTIFY (I/O error, err_mask=0x5)
[   16.888085] ata3.01: qc timeout (cmd 0xec)
[   16.888147] ata3.01: failed to IDENTIFY (I/O error, err_mask=0x5)
[   46.888086] ata3.01: qc timeout (cmd 0xec)
[   46.888148] ata3.01: failed to IDENTIFY (I/O error, err_mask=0x5)
[   51.888100] ata3.00: qc timeout (cmd 0xec)
[   51.888160] ata3.00: failed to IDENTIFY (I/O error, err_mask=0x5)
[   61.888079] ata3.00: qc timeout (cmd 0xec)
[   61.888141] ata3.00: failed to IDENTIFY (I/O error, err_mask=0x5)
[   91.888089] ata3.00: qc timeout (cmd 0xec)
[   91.888152] ata3.00: failed to IDENTIFY (I/O error, err_mask=0x5)

ATAPI device connected:
[    1.882061] pata_isapnp 01:01.02: activated
[    1.893430] scsi2 : pata_isapnp
[    1.893719] ata3: PATA max PIO0 cmd 0x1e8 ctl 0x0 irq 11
[    6.892107] ata3.01: qc timeout (cmd 0xec)
[    6.892171] ata3.01: failed to IDENTIFY (I/O error, err_mask=0x5)
[   16.892079] ata3.01: qc timeout (cmd 0xec)
[   16.892138] ata3.01: failed to IDENTIFY (I/O error, err_mask=0x5)
[   46.892079] ata3.01: qc timeout (cmd 0xec)
[   46.892138] ata3.01: failed to IDENTIFY (I/O error, err_mask=0x5)
[   46.908586] ata3.00: ATAPI: ACER CD-767E/O, V1.5X, max PIO2, CDB intr
[   46.924570] ata3.00: configured for PIO0 (device error ignored)
[   46.926295] scsi 2:0:0:0: CD-ROM            ACER     CD-767E/O        1.5X PQ: 0 ANSI: 5
[   46.984519] sr0: scsi3-mmc drive: 6x/6x xa/form2 tray
[   46.984592] cdrom: Uniform CD-ROM driver Revision: 3.20

So don't skip ata_sff_softreset, just skip the reset part of ata_bus_softreset
if the ctl port is not available.

This makes IDE port on ES968 behave correctly:

No device connected:
[    4.670888] pata_isapnp 01:01.02: activated
[    4.673207] scsi host2: pata_isapnp
[    4.673675] ata3: PATA max PIO0 cmd 0x1e8 ctl 0x0 irq 11
[    7.081840] Adding 2541652k swap on /dev/sda2.  Priority:-1 extents:1 across:2541652k

ATAPI device connected:
[    4.704362] pata_isapnp 01:01.02: activated
[    4.706620] scsi host2: pata_isapnp
[    4.706877] ata3: PATA max PIO0 cmd 0x1e8 ctl 0x0 irq 11
[    4.872782] ata3.00: ATAPI: ACER CD-767E/O, V1.5X, max PIO2, CDB intr
[    4.888673] ata3.00: configured for PIO0 (device error ignored)
[    4.893984] scsi 2:0:0:0: CD-ROM            ACER     CD-767E/O        1.5X PQ: 0 ANSI: 5
[    7.015578] Adding 2541652k swap on /dev/sda2.  Priority:-1 extents:1 across:2541652k
Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org

drivers/ata/libata-sff.c

@@ -2008,6 +2008,7 @@ static int ata_bus_softreset(struct ata_port *ap, unsigned int devmask,
 
 	DPRINTK("ata%u: bus reset via SRST\n", ap->print_id);
 
+	if (ap->ioaddr.ctl_addr) {
 		/* software reset.  causes dev0 to be selected */
 		iowrite8(ap->ctl, ioaddr->ctl_addr);
 		udelay(20);	/* FIXME: flush */
@@ -2015,6 +2016,7 @@ static int ata_bus_softreset(struct ata_port *ap, unsigned int devmask,
 		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);
@@ -2215,10 +2217,6 @@ void ata_sff_error_handler(struct ata_port *ap)
 
 	spin_unlock_irqrestore(ap->lock, flags);
 
-	/* ignore ata_sff_softreset if ctl isn't accessible */
-	if (softreset == ata_sff_softreset && !ap->ioaddr.ctl_addr)
-		softreset = NULL;
-
 	/* ignore built-in hardresets if SCR access is not available */
 	if ((hardreset == sata_std_hardreset ||
 	     hardreset == sata_sff_hardreset) && !sata_scr_valid(&ap->link))