pata_hpt366: reimplement mode programming

Reimplement mode programming logic of pata_hpt366 such that it's
identical to that of IDE hpt366 driver.  The differences were...

* pata_hpt366 used 0xCFFF8FFFF to mask pio modes and 0x3FFFFFFF dma
  modes.  IDE hpt366 uses 0xC1F8FFFF for PIO, 0x303800FF for MWDMA and
  0x30070000 for UDMA.

* pata_hpt366 doesn't set 0x08000000 for PIO unless it's already set
  and always turns it on for MWDMA/UDMA.  IDE hpt366 doesn't bother
  with the bit.  It always uses what was there.

* IDE hpt366 always clears 0xC0000000.  pata_hpt366 doesn't.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_hpt366.c

@@ -30,7 +30,7 @@
 #define DRV_VERSION	"0.6.2"
 
 struct hpt_clock {
-	u8	xfer_speed;
+	u8	xfer_mode;
 	u32	timing;
 };
 
@@ -189,28 +189,6 @@ static unsigned long hpt366_filter(struct ata_device *adev, unsigned long mask)
 	return ata_bmdma_mode_filter(adev, mask);
 }
 
-/**
- *	hpt36x_find_mode	-	reset the hpt36x bus
- *	@ap: ATA port
- *	@speed: transfer mode
- *
- *	Return the 32bit register programming information for this channel
- *	that matches the speed provided.
- */
-
-static u32 hpt36x_find_mode(struct ata_port *ap, int speed)
-{
-	struct hpt_clock *clocks = ap->host->private_data;
-
-	while(clocks->xfer_speed) {
-		if (clocks->xfer_speed == speed)
-			return clocks->timing;
-		clocks++;
-	}
-	BUG();
-	return 0xffffffffU;	/* silence compiler warning */
-}
-
 static int hpt36x_cable_detect(struct ata_port *ap)
 {
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
@@ -226,25 +204,16 @@ static int hpt36x_cable_detect(struct ata_port *ap)
 	return ATA_CBL_PATA80;
 }
 
-/**
- *	hpt366_set_piomode		-	PIO setup
- *	@ap: ATA interface
- *	@adev: device on the interface
- *
- *	Perform PIO mode setup.
- */
-
-static void hpt366_set_piomode(struct ata_port *ap, struct ata_device *adev)
+static void hpt366_set_mode(struct ata_port *ap, struct ata_device *adev,
+			    u8 mode)
 {
+	struct hpt_clock *clocks = ap->host->private_data;
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
-	u32 addr1, addr2;
-	u32 reg;
-	u32 mode;
+	u32 addr1 = 0x40 + 4 * (adev->devno + 2 * ap->port_no);
+	u32 addr2 = 0x51 + 4 * ap->port_no;
+	u32 mask, reg;
 	u8 fast;
 
-	addr1 = 0x40 + 4 * (adev->devno + 2 * ap->port_no);
-	addr2 = 0x51 + 4 * ap->port_no;
-
 	/* Fast interrupt prediction disable, hold off interrupt disable */
 	pci_read_config_byte(pdev, addr2, &fast);
 	if (fast & 0x80) {
@@ -252,12 +221,43 @@ static void hpt366_set_piomode(struct ata_port *ap, struct ata_device *adev)
 		pci_write_config_byte(pdev, addr2, fast);
 	}
 
+	/* determine timing mask and find matching clock entry */
+	if (mode < XFER_MW_DMA_0)
+		mask = 0xc1f8ffff;
+	else if (mode < XFER_UDMA_0)
+		mask = 0x303800ff;
+	else
+		mask = 0x30070000;
+
+	while (clocks->xfer_mode) {
+		if (clocks->xfer_mode == mode)
+			break;
+		clocks++;
+	}
+	if (!clocks->xfer_mode)
+		BUG();
+
+	/*
+	 * Combine new mode bits with old config bits and disable
+	 * on-chip PIO FIFO/buffer (and PIO MST mode as well) to avoid
+	 * problems handling I/O errors later.
+	 */
 	pci_read_config_dword(pdev, addr1, &reg);
-	mode = hpt36x_find_mode(ap, adev->pio_mode);
-	mode &= ~0x8000000;	/* No FIFO in PIO */
-	mode &= ~0x30070000;	/* Leave config bits alone */
-	reg &= 0x30070000;	/* Strip timing bits */
-	pci_write_config_dword(pdev, addr1, reg | mode);
+	reg = ((reg & ~mask) | (clocks->timing & mask)) & ~0xc0000000;
+	pci_write_config_dword(pdev, addr1, reg);
+}
+
+/**
+ *	hpt366_set_piomode		-	PIO setup
+ *	@ap: ATA interface
+ *	@adev: device on the interface
+ *
+ *	Perform PIO mode setup.
+ */
+
+static void hpt366_set_piomode(struct ata_port *ap, struct ata_device *adev)
+{
+	hpt366_set_mode(ap, adev, adev->pio_mode);
 }
 
 /**
@@ -271,28 +271,7 @@ static void hpt366_set_piomode(struct ata_port *ap, struct ata_device *adev)
 
 static void hpt366_set_dmamode(struct ata_port *ap, struct ata_device *adev)
 {
-	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
-	u32 addr1, addr2;
-	u32 reg;
-	u32 mode;
-	u8 fast;
-
-	addr1 = 0x40 + 4 * (adev->devno + 2 * ap->port_no);
-	addr2 = 0x51 + 4 * ap->port_no;
-
-	/* Fast interrupt prediction disable, hold off interrupt disable */
-	pci_read_config_byte(pdev, addr2, &fast);
-	if (fast & 0x80) {
-		fast &= ~0x80;
-		pci_write_config_byte(pdev, addr2, fast);
-	}
-
-	pci_read_config_dword(pdev, addr1, &reg);
-	mode = hpt36x_find_mode(ap, adev->dma_mode);
-	mode |= 0x8000000;	/* FIFO in MWDMA or UDMA */
-	mode &= ~0xC0000000;	/* Leave config bits alone */
-	reg &= 0xC0000000;	/* Strip timing bits */
-	pci_write_config_dword(pdev, addr1, reg | mode);
+	hpt366_set_mode(ap, adev, adev->dma_mode);
 }
 
 static struct scsi_host_template hpt36x_sht = {