ide: check drive->present in ide_get_paired_drive()

* Change ide_get_paired_drive() to return NULL if peer device
  is not present and update all users accordingly.

While at it:

* ide_get_paired_drive() -> ide_get_pair_dev()

* Use ide_get_pair_dev() in cs5530.c, sc1200.c and via82cxxx.c.

There should be no functional changes caused by this patch.
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/arm/palm_bk3710.c

@@ -180,7 +180,7 @@ static void palm_bk3710_setpiomode(void __iomem *base, ide_drive_t *mate,
 	val32 |= (t2i << (dev ? 8 : 0));
 	writel(val32, base + BK3710_DATRCVR);
 
-	if (mate && mate->present) {
+	if (mate) {
 		u8 mode2 = ide_get_best_pio_mode(mate, 255, 4);
 
 		if (mode2 < mode)
@@ -230,7 +230,7 @@ static void palm_bk3710_set_pio_mode(ide_drive_t *drive, u8 pio)
 	 * Obtain the drive PIO data for tuning the Palm Chip registers
 	 */
 	cycle_time = ide_pio_cycle_time(drive, pio);
-	mate = ide_get_paired_drive(drive);
+	mate = ide_get_pair_dev(drive);
 	palm_bk3710_setpiomode(base, mate, is_slave, cycle_time, pio);
 }
 

drivers/ide/pci/cs5530.c

@@ -81,11 +81,11 @@ static void cs5530_set_pio_mode(ide_drive_t *drive, const u8 pio)
 static u8 cs5530_udma_filter(ide_drive_t *drive)
 {
 	ide_hwif_t *hwif = drive->hwif;
-	ide_drive_t *mate = &hwif->drives[(drive->dn & 1) ^ 1];
+	ide_drive_t *mate = ide_get_pair_dev(drive);
 	u16 *mateid = mate->id;
 	u8 mask = hwif->ultra_mask;
 
-	if (mate->present == 0)
+	if (mate == NULL)
 		goto out;
 
 	if (ata_id_has_dma(mateid) && __ide_dma_bad_drive(mate) == 0) {

drivers/ide/pci/cs5535.c

@@ -80,12 +80,12 @@ static void cs5535_set_speed(ide_drive_t *drive, const u8 speed)
 
 	/* Set the PIO timings */
 	if (speed < XFER_SW_DMA_0) {
-		ide_drive_t *pair = ide_get_paired_drive(drive);
+		ide_drive_t *pair = ide_get_pair_dev(drive);
 		u8 cmd, pioa;
 
 		cmd = pioa = speed - XFER_PIO_0;
 
-		if (pair->present) {
+		if (pair) {
 			u8 piob = ide_get_best_pio_mode(pair, 255, 4);
 
 			if (piob < cmd)

drivers/ide/pci/opti621.c

@@ -137,7 +137,7 @@ static u8 read_reg(int reg)
 static void opti621_set_pio_mode(ide_drive_t *drive, const u8 pio)
 {
 	ide_hwif_t *hwif = drive->hwif;
-	ide_drive_t *pair = ide_get_paired_drive(drive);
+	ide_drive_t *pair = ide_get_pair_dev(drive);
 	unsigned long flags;
 	u8 tim, misc, addr_pio = pio, clk;
 
@@ -153,7 +153,7 @@ static void opti621_set_pio_mode(ide_drive_t *drive, const u8 pio)
 
 	drive->drive_data = XFER_PIO_0 + pio;
 
-	if (pair->present) {
+	if (pair) {
 		if (pair->drive_data && pair->drive_data < drive->drive_data)
 			addr_pio = pair->drive_data - XFER_PIO_0;
 	}

drivers/ide/pci/sc1200.c

@@ -104,11 +104,11 @@ static void sc1200_tunepio(ide_drive_t *drive, u8 pio)
 static u8 sc1200_udma_filter(ide_drive_t *drive)
 {
 	ide_hwif_t *hwif = drive->hwif;
-	ide_drive_t *mate = &hwif->drives[(drive->dn & 1) ^ 1];
+	ide_drive_t *mate = ide_get_pair_dev(drive);
 	u16 *mateid = mate->id;
 	u8 mask = hwif->ultra_mask;
 
-	if (mate->present == 0)
+	if (mate == NULL)
 		goto out;
 
 	if (ata_id_has_dma(mateid) && __ide_dma_bad_drive(mate) == 0) {

drivers/ide/pci/siimage.c

@@ -245,7 +245,7 @@ static void sil_set_pio_mode(ide_drive_t *drive, u8 pio)
 
 	ide_hwif_t *hwif	= HWIF(drive);
 	struct pci_dev *dev	= to_pci_dev(hwif->dev);
-	ide_drive_t *pair	= ide_get_paired_drive(drive);
+	ide_drive_t *pair	= ide_get_pair_dev(drive);
 	u32 speedt		= 0;
 	u16 speedp		= 0;
 	unsigned long addr	= siimage_seldev(drive, 0x04);
@@ -259,7 +259,7 @@ static void sil_set_pio_mode(ide_drive_t *drive, u8 pio)
 	u8 unit			= drive->select.b.unit;
 
 	/* trim *taskfile* PIO to the slowest of the master/slave */
-	if (pair->present) {
+	if (pair) {
 		u8 pair_pio = ide_get_best_pio_mode(pair, 255, 4);
 
 		if (pair_pio < tf_pio)

drivers/ide/pci/via82cxxx.c

@@ -154,7 +154,7 @@ static void via_set_speed(ide_hwif_t *hwif, u8 dn, struct ide_timing *timing)
 static void via_set_drive(ide_drive_t *drive, const u8 speed)
 {
 	ide_hwif_t *hwif = drive->hwif;
-	ide_drive_t *peer = hwif->drives + (~drive->dn & 1);
+	ide_drive_t *peer = ide_get_pair_dev(drive);
 	struct pci_dev *dev = to_pci_dev(hwif->dev);
 	struct ide_host *host = pci_get_drvdata(dev);
 	struct via82cxxx_dev *vdev = host->host_priv;
@@ -173,7 +173,7 @@ static void via_set_drive(ide_drive_t *drive, const u8 speed)
 
 	ide_timing_compute(drive, speed, &t, T, UT);
 
-	if (peer->present) {
+	if (peer) {
 		ide_timing_compute(peer, peer->current_speed, &p, T, UT);
 		ide_timing_merge(&p, &t, &t, IDE_TIMING_8BIT);
 	}

include/linux/ide.h

@@ -1450,10 +1450,10 @@ static inline int hwif_to_node(ide_hwif_t *hwif)
 	return hwif->dev ? dev_to_node(hwif->dev) : -1;
 }
 
-static inline ide_drive_t *ide_get_paired_drive(ide_drive_t *drive)
+static inline ide_drive_t *ide_get_pair_dev(ide_drive_t *drive)
 {
-	ide_hwif_t *hwif	= HWIF(drive);
+	ide_drive_t *peer = &drive->hwif->drives[(drive->dn ^ 1) & 1];
 
-	return &hwif->drives[(drive->dn ^ 1) & 1];
+	return peer->present ? peer : NULL;
 }
 #endif /* _IDE_H */