T60 Ultrabay HDD working on UDMA2 only

[bessel]

(T60 2623-D6U) The harddrive I put in is a SATA Samsung 80G. Under Windows XP it was running on UDMA5. My linux distro is 2.6.17-13 debian testing. Below is what I've got when I run hdparm:

# hdparm -i /dev/hda

/dev/hda:

Model=SAMSUNG HM080JI, FwRev=YC100-04, SerialNo=S082J10L614166
Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs }
RawCHS=16383/16/63, TrkSize=34902, SectSize=554, ECCbytes=4
BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=off
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes: pio0 pio1 pio2 pio3 pio4
DMA modes: mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 *udma2
AdvancedPM=no WriteCache=enabled
Drive conforms to: ATA/ATAPI-7 T13 1532D revision 0: ATA/ATAPI-1 ATA/ATAPI-2 ATA/ATAPI-3 ATA/ATAPI-4 ATA/ATAPI-5 ATA/ATAPI-6 ATA/ATAPI-7

* signifies the current active mode

and the benchmark:
# hdparm -tT /dev/hda

/dev/hda:
Timing cached reads: 4468 MB in 2.00 seconds = 2236.47 MB/sec
Timing buffered disk reads: 82 MB in 3.02 seconds = 27.14 MB/sec

A bit on the slow side, huh? I am not really sure, but it seems the DMA mode under Linux is not the same as what it should be, unless Windows XP was reporting wrongly. BTW, the Windows was the original one installed on /dev/sda (main harddrive) and linux was on the ultrabay harddrive /dev/hda.

All comments or suggestions are welcome! Thanks.