CD-ripping using ioctl() does not work when DMA is disabled (ide-cd)

CD-ripping using ioctl() does not work when DMA is disabled (ide-cd)

[Johan Billing]

In kernel 2.6.8, my old TEAC CD-532E-A CD-ROM is blacklisted and DMA is 
automatically disabled. When I try to rip an audio CD using cdparanoia, 
all I get is a silent wav file full of zeroes. I know that there was 
some discussions about this on the list during the summer in conjunction 
with the "dropping to single frame DMA" issue, but I think I have some 
new information to add...

I investigated the cdparanoia source a bit and was able to pinpoint the 
problem a bit more. cdparanoia uses the ioctl() interface with 
CDROMREADAUDIO to read data from the CD and normally tries to read 6 or 
8 frames at a time. The problem is that only the first read frame 
contains valid data, the others are blank and only contain zeroes. If I 
disable error correction and only read one frame at a time ("cdparanoia 
-n1 -Z") it seems to work fine. If I defy the blacklist and turn DMA on 
using "hdparm -d1", cdparanoia can read multiple frames without any 
problems.

So in conclusion, this seems to be a problem that only occurs when 
reading multiple frames using ioctl() with DMA off. I hope that this 
will help find and fix the problem.

/Johan

Re: CD-ripping using ioctl() does not work when DMA is disabled (ide-cd)

[Peter Jones]

On Mon, 30 Aug 2004 21:48:23 +0200, Johan Billing <billing@df.lth.se> wrote:
> So in conclusion, this seems to be a problem that only occurs when
> reading multiple frames using ioctl() with DMA off. I hope that this
> will help find and fix the problem.

The simple fix, of course, is to not use cooked ioctl mode :)

This seems like a good time to mention that I've got a version
modified to use SG_IO, which can be found at
http://people.redhat.com/pjones/cdparanoia/ .  It still needs plenty
of testing before I merge any of that code in the main tree, though.

(Sorry about the double-reply, Johan, but I didn't want to leave you
off of the copy to l-k, even after I messed up on the first one)