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[what_if <jonathan.a.phelps@xxxxxxxxx>]

**Hack/workaround alert**

I had a similar problem with my computer.

I simply forced UDMA Mode 4 and ATAPI-5 in the BIOS instead of "Auto".
This fixed my problem and may fix yours as linux then is forced to use that speed irregardless of the 80-wire cable being detected.

-- 
Wrong UDMA mode due to error in 40/80 wire cable detection
https://bugs.launchpad.net/bugs/195221
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Status in Ubuntu: Invalid
Status in “linux” source package in Ubuntu: Fix Released
Status in “linux-source-2.6.22” source package in Ubuntu: Won't Fix

Bug description:
I have an Asus Eee PC 4GB laptop, and I am testing Ubuntu Hardy 8.04 (kernel 2.6.24-8) on it.

The computer has a 4GB SSD soldered to the motherboard. The disk is reported as UDMA66 capable, but is installed as UDMA33 because the system does not detect a 80 pin conductor.

I have tried adding kernel parameters (ide0=ata66 ide1=ata66) but these seems to be ignored. I have read that these parameters are just to instruct the kernel not to do the 40/80 wire test.

I have written a blog entry [http://ospatia.blogspot.com/2008/02/eee-pc-optimizar-el-disco-ssd.html] (in Spanish) with additional information (dmesg output, some tests with hdparm, ...) and I have found additioal people having same problem with fast (300x) Compact Flash cards.

dmesg output extract:

[   26.700245] ata2.00: ATA-4: SILICONMOTION SM223AC, , max UDMA/66
[   26.700256] ata2.00: 7815024 sectors, multi 0: LBA
[   26.700297] ata2.00: limited to UDMA/33 due to 40-wire cable
[   26.716208] ata2.00: configured for UDMA/33