From: Alan Cox <alan@lxorguk.ukuu.org.uk>

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 drivers/ata/ata_piix.c    |   29 ++++++++++++++++++++++++++++-
 drivers/ata/libata-core.c |    7 +++++++
 drivers/ata/pata_ali.c    |    2 +-
 include/linux/ata.h       |   14 ++++++++++++--
 4 files changed, 48 insertions(+), 4 deletions(-)

diff -puN drivers/ata/ata_piix.c~libata-add-40pin-short-cable-support-honour-drive drivers/ata/ata_piix.c
--- a/drivers/ata/ata_piix.c~libata-add-40pin-short-cable-support-honour-drive
+++ a/drivers/ata/ata_piix.c
@@ -93,7 +93,7 @@
 #include <linux/libata.h>
 
 #define DRV_NAME	"ata_piix"
-#define DRV_VERSION	"2.00ac6"
+#define DRV_VERSION	"2.00ac7"
 
 enum {
 	PIIX_IOCFG		= 0x54, /* IDE I/O configuration register */
@@ -566,6 +566,23 @@ module_param(force_pcs, int, 0444);
 MODULE_PARM_DESC(force_pcs, "force honoring or ignoring PCS to work around "
 		 "device mis-detection (0=default, 1=ignore PCS, 2=honor PCS)");
 
+struct ich_laptop {
+	u16 device;
+	u16 subvendor;
+	u16 subdevice;
+};
+
+/*
+ *	List of laptops that use short cables rather than 80 wire
+ */
+
+static const struct ich_laptop ich_laptop[] = {
+	/* devid, subvendor, subdev */
+	{ 0x27DF, 0x0005, 0x0280 },	/* ICH7 on Acer 5602WLMi */
+	/* end marker */
+	{ 0, }
+};
+
 /**
  *	piix_pata_cbl_detect - Probe host controller cable detect info
  *	@ap: Port for which cable detect info is desired
@@ -580,12 +597,22 @@ MODULE_PARM_DESC(force_pcs, "force honor
 static void ich_pata_cbl_detect(struct ata_port *ap)
 {
 	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
+	const struct ich_laptop *lap = &ich_laptop[0];
 	u8 tmp, mask;
 
 	/* no 80c support in host controller? */
 	if ((ap->udma_mask & ~ATA_UDMA_MASK_40C) == 0)
 		goto cbl40;
 
+	/* Check for specials - Acer Aspire 5602WLMi */
+	while (lap->device) {
+		if (lap->device == pdev->device &&
+		    lap->subvendor == pdev->subsystem_vendor &&
+		    lap->subdevice == pdev->subsystem_device)
+		    	return ATA_CBL_PATA40_SHORT;
+		lap++;
+	}
+
 	/* check BIOS cable detect results */
 	mask = ap->port_no == 0 ? PIIX_80C_PRI : PIIX_80C_SEC;
 	pci_read_config_byte(pdev, PIIX_IOCFG, &tmp);
diff -puN drivers/ata/libata-core.c~libata-add-40pin-short-cable-support-honour-drive drivers/ata/libata-core.c
--- a/drivers/ata/libata-core.c~libata-add-40pin-short-cable-support-honour-drive
+++ a/drivers/ata/libata-core.c
@@ -3093,6 +3093,13 @@ static void ata_dev_xfermask(struct ata_
 	 */
 	if (ap->cbl == ATA_CBL_PATA40)
 		xfer_mask &= ~(0xF8 << ATA_SHIFT_UDMA);
+	/* Apply drive side cable rule. Unknown or 80 pin cables reported
+	 * host side are checked drive side as well. Cases where we know a
+	 * 40wire cable is used safely for 80 are not checked here.
+	 */
+        if (ata_drive_40wire(dev->id) && (ap->cbl == ATA_CBL_PATA_UNK || ap->cbl == ATA_CBL_PATA80))
+		xfer_mask &= ~(0xF8 << ATA_SHIFT_UDMA);
+
 
 	xfer_mask &= ata_pack_xfermask(dev->pio_mask,
 				       dev->mwdma_mask, dev->udma_mask);
diff -puN drivers/ata/pata_ali.c~libata-add-40pin-short-cable-support-honour-drive drivers/ata/pata_ali.c
--- a/drivers/ata/pata_ali.c~libata-add-40pin-short-cable-support-honour-drive
+++ a/drivers/ata/pata_ali.c
@@ -78,7 +78,7 @@ static int ali_c2_cable_detect(struct at
 	   implement the detect logic */
 
 	if (ali_cable_override(pdev))
-		return ATA_CBL_PATA80;
+		return ATA_CBL_PATA40_SHORT;
 
 	/* Host view cable detect 0x4A bit 0 primary bit 1 secondary
 	   Bit set for 40 pin */
diff -puN include/linux/ata.h~libata-add-40pin-short-cable-support-honour-drive include/linux/ata.h
--- a/include/linux/ata.h~libata-add-40pin-short-cable-support-honour-drive
+++ a/include/linux/ata.h
@@ -200,8 +200,9 @@ enum {
 	ATA_CBL_NONE		= 0,
 	ATA_CBL_PATA40		= 1,
 	ATA_CBL_PATA80		= 2,
-	ATA_CBL_PATA_UNK	= 3,
-	ATA_CBL_SATA		= 4,
+	ATA_CBL_PATA40_SHORT	= 3,		/* 40 wire cable to high UDMA spec */
+	ATA_CBL_PATA_UNK	= 4,
+	ATA_CBL_SATA		= 5,
 
 	/* SATA Status and Control Registers */
 	SCR_STATUS		= 0,
@@ -342,6 +343,15 @@ static inline int ata_id_is_cfa(const u1
 	return 0;
 }
 
+static inline int ata_drive_40wire(const u16 *dev_id)
+{
+	if (ata_id_major_version(dev_id) >= 5 && ata_id_is_sata(dev_id))
+		return 0;	/* SATA */
+	if (dev_id[93] & 0x4000)
+		return 0;	/* 80 wire */
+	return 1;
+}
+
 static inline int atapi_cdb_len(const u16 *dev_id)
 {
 	u16 tmp = dev_id[0] & 0x3;
_