ata_piix: disallow UDMA 133 on ICH5 & ICH7

There is another outstanding issue with ata_piix.c.  Intel has never
officially supported anything faster than PATA 100MB/s.

But, the ata_piix.c driver "define" the ICH5 & ICH7 as UDMA6 (aka 133MB/s)
capable.  [ Well, no one has probably noticed it before, because there is bug
in do_pata_set_dmamode...  Just look at
libata_atapiix_enable_real_udma133.patch and you'll see what wrong with it.  ]

Here are Intel's datasheets for the affected chipsets: ICH5 Datasheet:
http://www.intel.com/design/chipsets/datashts/252516.htm (See note on page
183: "...  the ICH5 supports reads at the maximum rate of 100MB/s.")

ICH7 Datasheet: http://www.intel.com/design/chipsets/datashts/307013.htm (See
first note on page 190: "...  the ICH7 supports reads at the maximum rate of
100MB/s.")

They are two different ways to deal with it:

- Either -

1. replace all ich_pata_133 with ich_pata_100.
   (libata_atapiix_disable_udma6.diff - diff from 2.6.22 )

- Or -

2. keep all ich_pata_133 and fix the bug in "do_pata_set_dmamode".
   (libata_atapiix_enable_real_udma133.patch - diff from 2.6.22) If there are
   any concerns about the safety of the patch patch:
   http://lkml.org/lkml/2007/7/6/292 (It was already tested by an Intel
   employee, but I guess a bit more user input is necessary here...  )

This patch implements 1.

Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Jeff Garzik <jeff@garzik.org>
Cc: Tejun Heo <htejun@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/ata_piix.c

@@ -123,7 +123,7 @@ enum {
 	ich_pata_33		= 1,	/* ICH up to UDMA 33 only */
 	ich_pata_66		= 2,	/* ICH up to 66 Mhz */
 	ich_pata_100		= 3,	/* ICH up to UDMA 100 */
-	ich_pata_133		= 4,	/* ICH up to UDMA 133 */
+	/* ICH up to UDMA 133 is not supported */
 	ich5_sata		= 5,
 	ich6_sata		= 6,
 	ich6_sata_ahci		= 7,
@@ -199,7 +199,7 @@ static const struct pci_device_id piix_pci_tbl[] = {
 	{ 0x8086, 0x24CA, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
 	{ 0x8086, 0x24CB, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
 	/* Intel ICH5 */
-	{ 0x8086, 0x24DB, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_133 },
+	{ 0x8086, 0x24DB, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
 	/* C-ICH (i810E2) */
 	{ 0x8086, 0x245B, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
 	/* ESB (855GME/875P + 6300ESB) UDMA 100  */
@@ -207,7 +207,7 @@ static const struct pci_device_id piix_pci_tbl[] = {
 	/* ICH6 (and 6) (i915) UDMA 100 */
 	{ 0x8086, 0x266F, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
 	/* ICH7/7-R (i945, i975) UDMA 100*/
-	{ 0x8086, 0x27DF, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_133 },
+	{ 0x8086, 0x27DF, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
 	{ 0x8086, 0x269E, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
 	/* ICH8 Mobile PATA Controller */
 	{ 0x8086, 0x2850, PCI_ANY_ID, PCI_ANY_ID, 0, 0, ich_pata_100 },
@@ -505,7 +505,7 @@ static struct ata_port_info piix_port_info[] = {
 		.port_ops	= &ich_pata_ops,
 	},
 
-	/* ich_pata_133: 4 	ICH with full UDMA6 */
+	/* ich_pata_133: 4 - Not supported - */
 	{
 		.sht		= &piix_sht,
 		.flags		= PIIX_PATA_FLAGS | PIIX_FLAG_CHECKINTR,