Some time ago I built myself home media center on MythBuntu 8.04. It works exceptionally well… well, with one exception, if I may be excused. I could not watch my absolutely legally purchased DVDs at all – playback was choppy and jumpy, making watching movies anything but enjoyable.
If you found this post on google, you, probably, are about to give up. I was too. But I found a solution that worked for me. So, if you, like me, have seen zillions of webpages discussing the problem but none of solutions worked for you, keep reading (and please comment if this post helps you to solve your problem).
So the problem was that CD or DVD driver has no DMA enabled and hdparm would report an error:
HDIO_SET_DMA failed: Operation not permitted
when trying to enable DMA.
I have Intel-based HP desktop with SATA HDD and IDE DVD combo drive. No problem with HDD, but DVD got stuck in PIO mode and hdparm is no help anymore. I have modules ata_piix and libata loaded.
After scanning though many discussions and FAQs, I finally found the most accurate description of the problem that offered a way to fix it. So I did exactly what they told:
# echo options libata atapi_enabled=1>/etc/modprobe.d/atapienable # update-initramfs -u
and added
combined_mode=libata
option to kernel line in grub’s menu.lst
After reboot DVD drive was finally in UDMA mode!
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