Trouble getting the DMA work in IDE Driver in kernel 2.4.2

Hi,
I am having some trouble getting the drivers
for the IDE/ATA 100 ( iam using cmd 649 & and an IBM
Deskstar )work in the DMA mode running kernel 2.4.2
on a PPC405GP.
If anybody has seen this problem, or has a fix for it
please respond.
I tried to enable the DMA using hdparam -d1 /dev/hda
but it fails. I  looked into the code and put some
printk's and found that the dma_base is set to 0 in
the file ide-dma.cin the function
ide_get_or_set_dma_base where it goes to
the default case of the switch statement. Which
results  in failure of the ioctl call to set the DMA
from hdparm.
What I understood is that the cmd649 is recognised as
a simplex device because of which the dma_base is set
to zero, but could not understand why ?

thanks in advance
SUKESH



Below is the boot up message log..
-----------------------------------
CMD649: IDE controller on PCI bus 00 dev 18

PCI: Enabling device 00:03.0 (0000 -> 0001)
CMD649: chipset revision 2
CMD649: not 100% native mode: will probe irqs later
CMD649: simplex device: DMA disabled
ide0: BM-DMA at 0x0060-0x0067, BIOS settings:

hda:pio, hdb:pio

ide1: BM-DMA at 0x0068-0x006f, BIOS settings:

hdc:pio, hdd:pio

hda: probing with STATUS(0x50) instead of

ALTSTATUS(0xff)

hda: IC35L040AVER07-0, ATA DISK drive
hda: IRQ probe failed (0x0)
hdb: probing with STATUS(0x00) instead of

ALTSTATUS(0xff)

hdb: IRQ probe failed (0x0)
hdb: probing with STATUS(0x00) instead of

ALTSTATUS(0xff)

hdb: IRQ probe failed (0x0)
ide: Assuming 33MHz system bus speed for PIO modes;

override with
idebus=xx

ide0 at 0x040-0x047,0x246 on irq 30
hda: 80418240 sectors (41174 MB) w/1916KiB Cache,

CHS=79780/16/63

Partition check:
hda: unknown partition table

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