hdd not accepting dma mode

[Vladimir Kosovac]

Hi all. Just installed RHEL 4 ES (update 2) on a laptop that used to run FC4
and FC5 rawhide really nice. With Enterprise however, hda won't turn on DMA
mode and reads are extremelly slow:
_________________________________________________________
hdparm -T /dev/hda

/dev/hda:
 Timing cached reads:   1888 MB in  2.00 seconds = 942.26 MB/sec
----------------------------------------------------------------------------------------------------
hdparm -t /dev/hda

/dev/hda:
 Timing buffered disk reads:    4 MB in  3.81 seconds =   1.05 MB/sec
(!!!!!!!!)
------------------------------------------------------------------------------------------------------------------

If I try

hdparm -d1 /dev/hda

I get the following error:

/dev/hda:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)

I've done a bit of Googling and searched bugzilla but haven't found anything
useful. Can someone point me in the rigth direction? Below is info that may
help:

OS: 2.6.9-22.0.1.EL (32 bit) (up-to-date)
CPU: AMD Turion(tm) 64
IDE: 00:14.1 IDE interface: ATI Technologies Inc Standard Dual Channel PCI
IDE Controller ATI
HDD: /dev/hda:
 multcount    = 16 (on)
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  0 (off)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    = 256 (on)
 geometry     = 65535/16/63, sectors = 60011642880, start = 0

 Model=TOSHIBA MK6025GAS, FwRev=KA201A, SerialNo=85GY4091S
 Config={ Fixed } ===> /* This is a bit of a worry */
 RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=48
 BuffType=unknown, BuffSize=0kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=117210240
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4
 DMA modes:  sdma0 sdma1 sdma2 mdma0 mdma1 mdma2
 UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
 AdvancedPM=yes: unknown setting WriteCache=enabled
 Drive conforms to: device does not report version: ===> /* This too */
 * signifies the current active mode
================================================================
Appologies for a novel in place of an email.

Cheers, V