hpt366: use correct enablebits for HPT36x

The HPT36x chips finally turned out to have the channel enable bits -- however,
badly implemented.  Make use of them despite it's probably only going to burden
the driver's code -- assuming both channels are always enabled by the HighPoint
BIOS anyway...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Acked-by: Linas Vepstas <linas@austin.ibm.com>
Cc: michal.kepien@poczta.onet.pl
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/pci/hpt366.c

@@ -1,5 +1,5 @@
 /*
- * linux/drivers/ide/pci/hpt366.c		Version 1.05	Jun 26, 2007
+ * linux/drivers/ide/pci/hpt366.c		Version 1.06	Jun 27, 2007
  *
  * Copyright (C) 1999-2003		Andre Hedrick <andre@linux-ide.org>
  * Portions Copyright (C) 2001	        Sun Microsystems, Inc.
@@ -1514,18 +1514,28 @@ static int __devinit init_setup_hpt366(struct pci_dev *dev, ide_pci_device_t *d)
 		goto init_single;
 
 	/*
-	 * HPT36x chips are single channel and
-	 * do not seem to have the channel enable bit...
+	 * HPT36x chips have one channel per function and have
+	 * both channel enable bits located differently and visible
+	 * to both functions -- really stupid design decision... :-(
+	 * Bit 4 is for the primary channel, bit 5 for the secondary.
 	 */
 	d->channels = 1;
-	d->enablebits[0].reg = 0;
+	d->enablebits[0].mask = d->enablebits[0].val = 0x10;
 
 	if ((dev2 = pci_get_slot(dev->bus, dev->devfn + 1)) != NULL) {
-	  	u8  pin1 = 0, pin2 = 0;
+		u8  mcr1 = 0, pin1 = 0, pin2 = 0;
 		int ret;
 
 		pci_set_drvdata(dev2, info[rev]);
 
+		/*
+		 * Now we'll have to force both channels enabled if
+		 * at least one of them has been enabled by BIOS...
+		 */
+		pci_read_config_byte(dev, 0x50, &mcr1);
+		if (mcr1 & 0x30)
+			pci_write_config_byte(dev, 0x50, mcr1 | 0x30);
+
 		pci_read_config_byte(dev,  PCI_INTERRUPT_PIN, &pin1);
 		pci_read_config_byte(dev2, PCI_INTERRUPT_PIN, &pin2);
 		if (pin1 != pin2 && dev->irq == dev2->irq) {