2.4.21-rc1-ac2 Promise IDE DMA won't work

[Tabris]

I looked thru marc's archives, and i'm not finding anything specific to 
this problem, tho I do believe it is probably a known issue.

ASUS A7v266-E
PDC20265
LITE-ON LTR-32123S

only device on the Promise IDE is the cd-rw drive. have four hard drives 
on the VIA IDE.

running kernel 2.4.21-rc1-ac2 + preempt + rmap15g + i2c-sensors

burning now works using cdrecord ATAPI (previous was 2.4.21-pre5-ac3 
where the ide-scsi was too unstable)

at present, reading the cd drive takes 80+% of CPU system time...

I would like to be able to enable DMA. i tried doing it manually with 
hdparm. enabling 32-bit IO or enabling DMA would both make it just not 
work.
[root@tabriel root]# hdparm /dev/hdg

/dev/hdg:
 HDIO_GET_MULTCOUNT failed: Invalid argument
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  0 (off)
 keepsettings =  0 (off)
 readonly     =  1 (on)
 readahead    =  8 (on)
 HDIO_GETGEO failed: Invalid argument
[root@tabriel root]#
[root@tabriel root]# hdparm -I /dev/hdg

/dev/hdg:

ATAPI CD-ROM, with removable media
        Model Number:       LITE-ON LTR-32123S
        Serial Number:
        Firmware Revision:  XS0R
Standards:
        Used: ATAPI for CD-ROMs, SFF-8020i, r2.5
        Supported: CD-ROM ATAPI-2
Configuration:
        DRQ response: 50us.
        Packet size: 12 bytes
Capabilities:
        LBA, IORDY(cannot be disabled)
        DMA: *mdma0 mdma1 mdma2 udma0 udma1 udma2
             Cycle time: min=120ns recommended=120ns
        PIO: pio0 pio1 pio2 pio3 pio4
             Cycle time: no flow control=227ns  IORDY flow control=120ns
[root@tabriel root]#

any more info needed, just ask. any help much appreciated.

-- 
"Ignorance is the soil in which belief in miracles grows."
-- Robert G. Ingersoll