Can't activate DMA on Lite-On DVD
 

I can't activate DMA on any of my devices (DVD, HDD, or CD):

[root@er241 /home/er241]# hdparm -d1 /dev/hdd

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

[root@er241 /home/er241]# hdparm -I /dev/hdd

/dev/hdd:

ATAPI CD-ROM, with removable media
Model Number: LITEON DVD-ROM LTD-165H
Serial Number:
Firmware Revision: CH0J
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 udma3
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=120ns IORDY flow control=120ns

I can see that my DVD should support UDMA2 but it won't activate. My distribution is Linux From Scratch 4.1 with a 2.4.22 kernel.

Can anyone help me with this problem? I'm sure I was able to activate DMA under Mandrake 9.1

Thanks,

Ed

If its LFS you must have compiled your own kernel? There are some kernel options for enabling/disabling DMA you should check. I've got

CONFIG_BLK_DEV_IDEDMA_PCI=y
CONFIG_IDEDMA_PCI_AUTO=y
CONFIG_BLK_DEV_IDEDMA=y
CONFIG_IDEDMA_AUTO=y

I had those activated. What I forgot to mention is that I have an nVidia chipset motherboard. I also needed to activate the (new) AMD/nVidia DMA option that is hidden at the bottom of the IDE settings. All is good now and my DVD is UDMA2 and my harddisk UDMA5 :)

Thanks for the pointer.