sata_via: Correctly setup PIO/DMA for pata slave on vt6421.

Before only the timings for master were set. Datasheet can be found
here: ftp://ftp.vtbridge.org/Docs/Storage/DS_VT6421A_100_CCPL.PDF
Surprisingly, a slave drive works without this patch. According to the
datasheet, the controller by default derives the DMA mode from the
Set Features command issued to a drive. Not sure about the PIO
timings, though. The real problem is that the timings for the master
effectively are the ones tuned for the slave. If these support
different UDMA-settings, there is trouble, especially when the slave
supports a higher UDMA than the master.

Anyhow, using the same mechanism for both master and slave seems like
a good idea.
Signed-off-by: Bart Hartgers <bart.hartgers@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/sata_via.c

@@ -44,7 +44,7 @@
 #include <linux/libata.h>
 
 #define DRV_NAME	"sata_via"
-#define DRV_VERSION	"2.4"
+#define DRV_VERSION	"2.5"
 
 /*
  * vt8251 is different from other sata controllers of VIA.  It has two
@@ -392,14 +392,16 @@ static void vt6421_set_pio_mode(struct ata_port *ap, struct ata_device *adev)
 {
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
 	static const u8 pio_bits[] = { 0xA8, 0x65, 0x65, 0x31, 0x20 };
-	pci_write_config_byte(pdev, PATA_PIO_TIMING, pio_bits[adev->pio_mode - XFER_PIO_0]);
+	pci_write_config_byte(pdev, PATA_PIO_TIMING - adev->devno,
+			      pio_bits[adev->pio_mode - XFER_PIO_0]);
 }
 
 static void vt6421_set_dma_mode(struct ata_port *ap, struct ata_device *adev)
 {
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
 	static const u8 udma_bits[] = { 0xEE, 0xE8, 0xE6, 0xE4, 0xE2, 0xE1, 0xE0, 0xE0 };
-	pci_write_config_byte(pdev, PATA_UDMA_TIMING, udma_bits[adev->dma_mode - XFER_UDMA_0]);
+	pci_write_config_byte(pdev, PATA_UDMA_TIMING - adev->devno,
+			      udma_bits[adev->dma_mode - XFER_UDMA_0]);
 }
 
 static const unsigned int svia_bar_sizes[] = {