how to enable dma for my dvd drive?

[andcon]

Hi, i've finally managed to install a DVD player, but the picture is all jumpy, i was just wondering how to check whether DMA was enabled for my cd drives and if not how do I enable it?
I am using Red Hat 8.0 (psyche)

Thanks for any help

[sgs521]

you can smooth out the video by using hdparm.. however I cannot seem to find the site that tells how to do this.. I think there's a link to it somewhere in the forums here, however it might take some searching.. just search for dvd in the forums.. you'll come acorss a lot of good info on this.. :)

[Icarus]

Red Hat 8.0 took a different way of doing this, sorta...more steps are needed now...

Typically all you should need to do is (as root)

/sbin/hdparm -d1 /dev/hdb

or whatever your DVD device is...
But this doesn't work in RH8.0, you'll get this message for trying...

HDIO_SET_DMA failed: Operation not permitted

But I found the answer in the Red Hat 8.0 release notes (http://www.redhat.com/docs/manuals/linux/RHL-8.0-Manual/release-notes/x86/) at the very bottom...what you need to do is..."DMA is disabled on CD-ROM drives in this release in a different but more reliable way than previously. If you are sure that your CD-ROM drive is capable of IDE DMA, place the following line in the /etc/modules.conf file:
options ide-cd dma=1"

[MightyKC]

I did that and my hdparm -Tt score went from 13.36MB/sec to 1.67 MB/sec to INPUT/OUTPUT error. I have RH8 and 2 year old common hardware.
How can I fix this? Why does xine still play (poorly) When hdparm can't get a reading from the dvd drive?