ata: pata_hpt37x: disable primary channel on HPT371

The HPT371 chip physically has only one channel, the secondary one,
however the primary channel registers do exist! Thus we have to
manually disable the non-existing channel if the BIOS hasn't done this
already. Similarly to the pata_hpt3x2n driver, always disable the
primary channel.

Fixes: 669a5db411 ("[libata] Add a bunch of PATA drivers.")
Cc: stable@vger.kernel.org
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

drivers/ata/pata_hpt37x.c

@@ -919,6 +919,20 @@ static int hpt37x_init_one(struct pci_dev *dev, const struct pci_device_id *id)
 	irqmask &= ~0x10;
 	pci_write_config_byte(dev, 0x5a, irqmask);
 
+	/*
+	 * HPT371 chips physically have only one channel, the secondary one,
+	 * but the primary channel registers do exist!  Go figure...
+	 * So,  we manually disable the non-existing channel here
+	 * (if the BIOS hasn't done this already).
+	 */
+	if (dev->device == PCI_DEVICE_ID_TTI_HPT371) {
+		u8 mcr1;
+
+		pci_read_config_byte(dev, 0x50, &mcr1);
+		mcr1 &= ~0x04;
+		pci_write_config_byte(dev, 0x50, mcr1);
+	}
+
 	/*
 	 * default to pci clock. make sure MA15/16 are set to output
 	 * to prevent drives having problems with 40-pin cables. Needed