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[Bug 195221] Re: Wrong UDMA mode due to error in 40/80 wire cable detection

To: ubuntu-eeepc@xxxxxxxxxxxxxxxxxxx
From: Matt Austin <mail@xxxxxxxxxxxxxxxx>
Date: Sat, 02 Aug 2008 13:45:10 -0000
Reply-to: Bug 195221 <195221@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx

Forgot mention that the kernel version is 2.6.26-5-generic.

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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: Triaged
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