*FIXED* DMA Support for CDROM's on VIA 82Cxxx

[James Gray]

For the archives to hopefully save others the pain.

I have a Asus K8VSE Deluxe motherboard with a single SATA (boot) drive and a 
single CDRW+DVDROM combo drive as hda (Master on 1st IDE).

Here's the relevant lines from lspci (bus ID's left out for the sake of 
bandwidth):

$lspci
Host bridge: VIA Technologies, Inc. VT8385 [K8T800 AGP] Host Bridge (rev 01)
PCI bridge: VIA Technologies, Inc. VT8237 PCI bridge [K8T800 South]
...
IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C
               PIPC Bus Master IDE (rev 06)

The system is running a standard Ubuntu/Kubuntu AMD64-K8 kernel:
$uname -a
Linux frodo 2.6.10-5-amd64-k8 #1 Thu Aug 18 22:36:46 UTC 2005 x86_64 
GNU/Linux

However with a standard Ubuntu/Kubuntu installation hdparm would not permit 
me to enable DMA support for /dev/hda (the CDRW etc).  As you can imagine 
this made buring CD's and reading/ripping CD's a real headache.

***********************************************
**** A kernel recompile is NOT necessary!! ****
***********************************************

You simply need to edit the /etc/modules file as follows:
1. REMOVE (or comment out) the line:
   ide-generic
2. Add following line *ABOVE* all of the ide-* lines (probably 1st line
   under the comments section):
   via82cxxx
   
Now simply reboot and verify "sudo hdparm -d1 /dev/hda" doesn't return an 
error and that /dev/hda has DMA enabled (sudo hdparm /dev/hda).  Voila!

To permanently configure /dev/hda with DMA support, edit /etc/hdparm.conf:
/dev/hda {
    dma = on
}

And here's some keywords for google to grok:
ubuntu kubuntu via cdrom DMA VT82C586A/B/VT82C686/A/B/VT823x/A/C

Have fun folks :)

James
-- 
Nothing compares to you <--> Hey, I'm not a poetry song
                -- anagrama
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