Re: [vox-tech] DVD issues

[Ken Bloom <kaMAPSbloom@ucdavis.edu>]

On Wed, 11 Aug 2004 11:06:16 -0700
Jonathan Stickel <jjstickel@sbcglobal.net> wrote:

> dylan wrote:
> > Hi everyone,
> > 
> > I was recently messing about with DVD playback on linux, and was
> > less than impressed with the quality- i.e. playback was at about 75%
> > speed. after some googling i came to the conclusion that I had 2
> > options: 1 get a better video card  or 2, fix the DMA settings on
> > the drive with hdparm... (the xv extension to X11 was already
> > installed)
> > 
> > 
> > the initial output from hdparm was as follows:
> > linux:/var/log # hdparm /dev/dvd
> > ---------------------
> > /dev/dvd: 
> >  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    = 256 (on)
> >  HDIO_GETGEO failed: Invalid argument
> > ---------------------
> > 
> > i tried a couple of combinations of turning on DMA, as well as
> > toggling the other settings. Any setting other than the default lead
> > to a non-functioning DVD drive, and the following lines in
> > /var/log/messages:---------------------
> > Aug 10 22:40:00 linux kernel: hdd: drive_cmd: status=0x51 {
> > DriveReady SeekComplete Error }
> > Aug 10 22:40:00 linux kernel: hdd: drive_cmd: error=0x04Aborted
> > Command---------------------
> > 
> > I have ordered a new video card for this machine, as the integrated
> > video is awful. perhaps this will solve my problems. however, is it
> > normal for a modern DVD drive like this one refuse to accept DMA
> > transfers?
> > 
> 
> How "modern" is it?  Booting up a few machines lately, I've seen a 
> kernel message about the cdrom (admittedly old) being "blacklisted"
> and therefore dma was set to be off.
> 
> On another list, I recently saw a long thread about dma not working
> for a dvdrw drive.  The problem ended up being an improper kernel 
> configuration, specifically the motherboard chipset drivers were not 
> compiled into the kernel. From what I understand, hdparm is
> unnecessary other than a diagnostic tool as long as the kernel is
> correctly compiled for your hardware.

when something is blacklisted, that means hotplug has it listed in
/etc/hotplug/blacklist, which tells hotplug not to load it. As the
comment at the top says:

#
# Listing a module here prevents the hotplug scripts from loading it.
# Usually that'd be so that some other driver will bind it instead,
# no matter which driver happens to get probed first.  Sometimes user
# mode tools can also control driver binding.
#
# Syntax:  driver name alone (without any spaces) on a line. Other
# lines are ignored.
#

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