Remove Asus EEE UDMA/33 limitation.

Dave Jones
2008-05-02T15:45:22Z

The Asus Eee PC prints this during bootup..

ata2.00: limited to UDMA/33 due to 40-wire cable
Which is unfortunate, as it has..
ata2.00: ATA-4: SILICONMOTION SM223AC, , max UDMA/66

I believe there actually is no cable, and the flash is directly
connected to the controller.

[root@eee ~]# hdparm -t /dev/sda

/dev/sda:
Timing buffered disk reads: 64 MB in 3.08 seconds = 20.76 MB/sec

With the patch below it returns..

/dev/sda:
Timing buffered disk reads: 76 MB in 3.04 seconds = 25.04 MB/sec

Signed-off-by: Dave Jones <davej@redhat.com>

--- linux-2.6.24.noarch/drivers/ata/ata_piix.c~ 2008-03-31 23:43:05.000000000 -0400
+++ linux-2.6.24.noarch/drivers/ata/ata_piix.c 2008-03-31 23:44:34.000000000 -0400
@@ -716,6 +716,7 @@ struct ich_laptop {

static const struct ich_laptop ich_laptop[] = {
/* devid, subvendor, subdev */
+ { 0x2653, 0x1043, 0x82d8 }, /* ICH6M on Asus Eee PC */
{ 0x27DF, 0x0005, 0x0280 }, /* ICH7 on Acer 5602WLMi */
{ 0x27DF, 0x1025, 0x0102 }, /* ICH7 on Acer 5602aWLMi */
{ 0x27DF, 0x1025, 0x0110 }, /* ICH7 on Acer 3682WLMi */

--