On Tue, 30 Oct 2007 15:14:39 +0000
Daniel Drake [off-list ref] wrote:

Hi Alan,

In 2.6.23 and previous, CD writing works fine on my system. I'm using 
ata_piix on:

00:1f.2 IDE interface: Intel Corporation 82801GBM/GHM (ICH7 Family) SATA 
IDE Controller (rev 01)

When I'm running CD writing utilities, I sometimes see this message in 
the kernel logs:
	ata2.00: 66 bytes trailing data
Things do work fine though.

By luck in part I suspect. That shouldn't be happening and indicates
something is very wrong. With the fifo buffers set right that may well
get worse.

git bisect lead me to commit 2db78dd302d26d242d3e8e5c4c5024b6c3ea93c2 as 
the culprit.

Author: Alan Cox [off-list ref]
Date:   Tue Oct 2 13:53:04 2007 -0700

     libata_scsi: Fix ATAPI transfer lengths

     Some controller variants snoop the ATAPI length value for Packet
     transfers to do state machine and FIFO management. Thus we want to
     set it properly, even for cases where it is otherwise meaningless.

Any ideas?

Not immediately - but if you've got wrong transfer lengths its a
candidate for this.

Ok lets start with the basics

If you mount a CD and use it does it work
If you use cdrecord does it work ?

What vendor drive and does it seem to be a specific box/drive that
triggers this ?

Alan