diff --git a/drivers/ide/ide-dma.c b/drivers/ide/ide-dma.c
index 4703837bf1fcdab9b6523c2fa4d5ff70bccd50a3..7568c3e81f2f3fcef0ba7d76a3ce5f057f206573 100644
--- a/drivers/ide/ide-dma.c
+++ b/drivers/ide/ide-dma.c
@@ -968,11 +968,6 @@ void ide_setup_dma(ide_hwif_t *hwif, unsigned long base, unsigned num_ports)
 
 	hwif->dma_base = base;
 
-	if (hwif->mate)
-		hwif->dma_master = hwif->channel ? hwif->mate->dma_base : base;
-	else
-		hwif->dma_master = base;
-
 	if (!(hwif->dma_command))
 		hwif->dma_command	= hwif->dma_base;
 	if (!(hwif->dma_vendor1))
@@ -1014,8 +1009,6 @@ void ide_setup_dma(ide_hwif_t *hwif, unsigned long base, unsigned num_ports)
 		       hwif->drives[1].name, (dma_stat & 0x40) ? "DMA" : "pio");
 	}
 	printk("\n");
-
-	BUG_ON(!hwif->dma_master);
 }
 
 EXPORT_SYMBOL_GPL(ide_setup_dma);
diff --git a/drivers/ide/ide.c b/drivers/ide/ide.c
index 54943da6e4e5cfa45c80ac73a86f6c9de3a10769..9ab5458fe950eee798f3371f4e7a0368896d81a6 100644
--- a/drivers/ide/ide.c
+++ b/drivers/ide/ide.c
@@ -468,7 +468,6 @@ static void ide_hwif_restore(ide_hwif_t *hwif, ide_hwif_t *tmp_hwif)
 #endif
 
 	hwif->dma_base			= tmp_hwif->dma_base;
-	hwif->dma_master		= tmp_hwif->dma_master;
 	hwif->dma_command		= tmp_hwif->dma_command;
 	hwif->dma_vendor1		= tmp_hwif->dma_vendor1;
 	hwif->dma_status		= tmp_hwif->dma_status;
@@ -602,7 +601,6 @@ void ide_unregister(unsigned int index)
 		(void) ide_release_dma(hwif);
 
 		hwif->dma_base = 0;
-		hwif->dma_master = 0;
 		hwif->dma_command = 0;
 		hwif->dma_vendor1 = 0;
 		hwif->dma_status = 0;
diff --git a/drivers/ide/pci/cmd64x.c b/drivers/ide/pci/cmd64x.c
index bc553337b1be38548d155ed6ea4db0fbffa417e0..f3613bac9dbeb778ab68b659c4568d563c358783 100644
--- a/drivers/ide/pci/cmd64x.c
+++ b/drivers/ide/pci/cmd64x.c
@@ -333,14 +333,15 @@ static void cmd64x_set_dma_mode(ide_drive_t *drive, const u8 speed)
 static int cmd648_ide_dma_end (ide_drive_t *drive)
 {
 	ide_hwif_t *hwif	= HWIF(drive);
+	unsigned long base	= hwif->dma_base - (hwif->channel * 8);
 	int err			= __ide_dma_end(drive);
 	u8  irq_mask		= hwif->channel ? MRDMODE_INTR_CH1 :
 						  MRDMODE_INTR_CH0;
-	u8  mrdmode		= inb(hwif->dma_master + 0x01);
+	u8  mrdmode		= inb(base + 1);
 
 	/* clear the interrupt bit */
 	outb((mrdmode & ~(MRDMODE_INTR_CH0 | MRDMODE_INTR_CH1)) | irq_mask,
-	     hwif->dma_master + 0x01);
+	     base + 1);
 
 	return err;
 }
@@ -365,10 +366,11 @@ static int cmd64x_ide_dma_end (ide_drive_t *drive)
 static int cmd648_ide_dma_test_irq (ide_drive_t *drive)
 {
 	ide_hwif_t *hwif	= HWIF(drive);
+	unsigned long base	= hwif->dma_base - (hwif->channel * 8);
 	u8 irq_mask		= hwif->channel ? MRDMODE_INTR_CH1 :
 						  MRDMODE_INTR_CH0;
 	u8 dma_stat		= inb(hwif->dma_status);
-	u8 mrdmode		= inb(hwif->dma_master + 0x01);
+	u8 mrdmode		= inb(base + 1);
 
 #ifdef DEBUG
 	printk("%s: dma_stat: 0x%02x mrdmode: 0x%02x irq_mask: 0x%02x\n",
diff --git a/drivers/ide/pci/hpt366.c b/drivers/ide/pci/hpt366.c
index df14d692743cd4bb26b1336482857990a5364ecd..d3826a66834d370e070ed5ee72b6064b589c82a6 100644
--- a/drivers/ide/pci/hpt366.c
+++ b/drivers/ide/pci/hpt366.c
@@ -894,32 +894,33 @@ static int hpt374_ide_dma_end(ide_drive_t *drive)
 
 static void hpt3xxn_set_clock(ide_hwif_t *hwif, u8 mode)
 {
-	u8 scr2 = inb(hwif->dma_master + 0x7b);
+	unsigned long base = hwif->extra_base;
+	u8 scr2 = inb(base + 0x6b);
 
 	if ((scr2 & 0x7f) == mode)
 		return;
 
 	/* Tristate the bus */
-	outb(0x80, hwif->dma_master + 0x73);
-	outb(0x80, hwif->dma_master + 0x77);
+	outb(0x80, base + 0x63);
+	outb(0x80, base + 0x67);
 
 	/* Switch clock and reset channels */
-	outb(mode, hwif->dma_master + 0x7b);
-	outb(0xc0, hwif->dma_master + 0x79);
+	outb(mode, base + 0x6b);
+	outb(0xc0, base + 0x69);
 
 	/*
 	 * Reset the state machines.
 	 * NOTE: avoid accidentally enabling the disabled channels.
 	 */
-	outb(inb(hwif->dma_master + 0x70) | 0x32, hwif->dma_master + 0x70);
-	outb(inb(hwif->dma_master + 0x74) | 0x32, hwif->dma_master + 0x74);
+	outb(inb(base + 0x60) | 0x32, base + 0x60);
+	outb(inb(base + 0x64) | 0x32, base + 0x64);
 
 	/* Complete reset */
-	outb(0x00, hwif->dma_master + 0x79);
+	outb(0x00, base + 0x69);
 
 	/* Reconnect channels to bus */
-	outb(0x00, hwif->dma_master + 0x73);
-	outb(0x00, hwif->dma_master + 0x77);
+	outb(0x00, base + 0x63);
+	outb(0x00, base + 0x67);
 }
 
 /**
diff --git a/drivers/ide/pci/pdc202xx_old.c b/drivers/ide/pci/pdc202xx_old.c
index e09742e2ba592607e31dd3356099fabf8fae5ea8..22c7a7533b696dd9785975e775b24d18a84c90cb 100644
--- a/drivers/ide/pci/pdc202xx_old.c
+++ b/drivers/ide/pci/pdc202xx_old.c
@@ -162,7 +162,7 @@ static u8 pdc202xx_old_cable_detect (ide_hwif_t *hwif)
  */
 static void pdc_old_enable_66MHz_clock(ide_hwif_t *hwif)
 {
-	unsigned long clock_reg = hwif->dma_master + 0x11;
+	unsigned long clock_reg = hwif->extra_base + 0x01;
 	u8 clock = inb(clock_reg);
 
 	outb(clock | (hwif->channel ? 0x08 : 0x02), clock_reg);
@@ -170,7 +170,7 @@ static void pdc_old_enable_66MHz_clock(ide_hwif_t *hwif)
 
 static void pdc_old_disable_66MHz_clock(ide_hwif_t *hwif)
 {
-	unsigned long clock_reg = hwif->dma_master + 0x11;
+	unsigned long clock_reg = hwif->extra_base + 0x01;
 	u8 clock = inb(clock_reg);
 
 	outb(clock & ~(hwif->channel ? 0x08 : 0x02), clock_reg);
@@ -193,7 +193,7 @@ static void pdc202xx_old_ide_dma_start(ide_drive_t *drive)
 	if (drive->media != ide_disk || drive->addressing == 1) {
 		struct request *rq	= HWGROUP(drive)->rq;
 		ide_hwif_t *hwif	= HWIF(drive);
-		unsigned long high_16   = hwif->dma_master;
+		unsigned long high_16	= hwif->extra_base - 16;
 		unsigned long atapi_reg	= high_16 + (hwif->channel ? 0x24 : 0x20);
 		u32 word_count	= 0;
 		u8 clock = inb(high_16 + 0x11);
@@ -212,7 +212,7 @@ static int pdc202xx_old_ide_dma_end(ide_drive_t *drive)
 {
 	if (drive->media != ide_disk || drive->addressing == 1) {
 		ide_hwif_t *hwif	= HWIF(drive);
-		unsigned long high_16	= hwif->dma_master;
+		unsigned long high_16	= hwif->extra_base - 16;
 		unsigned long atapi_reg	= high_16 + (hwif->channel ? 0x24 : 0x20);
 		u8 clock		= 0;
 
@@ -228,7 +228,7 @@ static int pdc202xx_old_ide_dma_end(ide_drive_t *drive)
 static int pdc202xx_old_ide_dma_test_irq(ide_drive_t *drive)
 {
 	ide_hwif_t *hwif	= HWIF(drive);
-	unsigned long high_16	= hwif->dma_master;
+	unsigned long high_16	= hwif->extra_base - 16;
 	u8 dma_stat		= inb(hwif->dma_status);
 	u8 sc1d			= inb(high_16 + 0x001d);
 
@@ -271,7 +271,7 @@ static void pdc202xx_dma_timeout(ide_drive_t *drive)
 
 static void pdc202xx_reset_host (ide_hwif_t *hwif)
 {
-	unsigned long high_16	= hwif->dma_master;
+	unsigned long high_16	= hwif->extra_base - 16;
 	u8 udma_speed_flag	= inb(high_16 | 0x001f);
 
 	outb(udma_speed_flag | 0x10, high_16 | 0x001f);
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 9a6a41e7079ff942ec4d204ae20011ee7987d6a2..1fb03b6306761a7d2edea057d6f37ab061ba261f 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -766,7 +766,6 @@ typedef struct hwif_s {
 	int		rqsize;		/* max sectors per request */
 	int		irq;		/* our irq number */
 
-	unsigned long	dma_master;	/* reference base addr dmabase */
 	unsigned long	dma_base;	/* base addr for dma ports */
 	unsigned long	dma_command;	/* dma command register */
 	unsigned long	dma_vendor1;	/* dma vendor 1 register */