Mailinglist Archive: opensuse-bugs (7967 mails)

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[Bug 237164] wrong DMA mode used for a DVD drive (UDMA66 instead of UDMA33)
  • From: bugzilla_noreply@xxxxxxxxxx
  • Date: Fri, 2 Feb 2007 15:04:46 -0700 (MST)
  • Message-id: <20070202220446.542D3FB9@xxxxxxxxxxxxxxxxxxxxxx>

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------- Comment #16 from rmuncrief@xxxxxxxxxxx 2007-02-02 15:04 MST -------

I'm sorry it has taken me so long to reply, but changing cable types caused all
hell to break loose under XP and it took awhile to characterize the problem, at
least as best I could without an oscilloscope, logic analyzer, or spectrum

To summarize, the LITE-ON drive was installed with the cable it came with, a
40c cable, and it was rock solid under XP. When I changed it to an 80c cable XP
set the drive to Ultra DMA mode 4 (UDMA66) but the drive became poly-unstable.
It could only intermittently read DVD/CDs. I was eventually able to make it
work but it appears the drive is shipped with a 40c cable for a reason, it is
highly susceptible to noise if you use an 80c cable and it operates in UDMA66

The Sony drive is using a 40c cable, and changing it to an 80c cable had no
effect on it. By the way, XP places the Sony drive in PIO mode no matter what
the cable, while openSuse places it in UDMA33. In any case, the Sony drive
works fine under both operating systems.

I didn't use the "hdparm -X udma2 /dev/hda" command you suggested but had
manually set the DMA mode to UDMA33 via Yast when I was using the DVD with the
40c cable and it did fix the problem. I believe the command you suggested does
the same thing.

In the end I got the DVD drive to work at UDMA66 by placing the Sony drive as a
slave on the same IDE cable as the DVD drive and removing the secondary IDE
cable. This seemed to eliminate enough noise to allow the DVD drive to work at
top speed. Keep in mind this is a very short summary, you just can't imagine
(or maybe you can) all the different data and power routing solutions I tried,
or how many different cables of all different types I tried.

The bottom line is that it appears some ODD manufacturers will sell products
whose hardware may report an operating speed that it's not actually capable of
operating at. At least the operating speed may vary depending upon the noise of
its environment, which is typically pretty bad in a PC cabinet. I believe your
plan to adjust to the actual tested operating speed is the only reliable

And by the way, I took the plunge. I converted all of my data to ext3 and am
using Suse 10.2 as my primary OS. Only 20GB of my 200GB of hard drive space is
now formatted as NTFS, and I'm using a translator program to access the ext3
partitions from Windows XP when I need to. I have installed VMWare Workstation
and am now running three separate Windows XP systems under openSuse to develop
my three web sites.

I'm still not completely happy with openSuse, and am having a lot of problems
getting anyone to truly care or do anything about the multimedia problems, but
I'm giving openSuse the best chance I can, and will do everything I can to
stick with it and make it work. However, if I'm still struggling a month or so
from now I will have to go out and buy Vista. I'm losing a lot of development
time trying to get openSuse to perform basic desktop OS tasks. On the other
hand, maybe it will work out and I can finally actually purchase a fully
functional version of Linux!. That will be a great day!.

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