I found this problem when burning DVDs using K3b (it uses growisofs to do the
work) with LG GSA-4167B drive:
Burn process completes without any problems, then K3b ejects and reloads the
tray, then it calculates MD5 checksum from the image. Then it starts reading the
DVD back to calculate MD5 checksum of it. The moment it starts to read, this
appears in dmesg:

hdd: irq timeout: status=0xd0 { Busy }
ide: failed opcode was: unknown
hdd: DMA disabled
hdd: ATAPI reset complete

And then it slowly reads the DVD in PIO mode. After about a hour, it finishes
with success. When I re-enable DMA mode ("hdparm -d1 /dev/hdd") immediately
after it was disabled, it works fine in - there are no more errors in the log
and the verification completes much sooner. I burnt 10 DVDs and it always does
exactly this.

Kernel is 2.6.13, the drive is (firmware is the latest version):
/dev/hdd:

 Model=HL-DT-ST DVDRAM GSA-4167B, FwRev=DL12, SerialNo=7076348C2984
 Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic }
 RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0
 BuffType=unknown, BuffSize=0kB, MaxMultSect=0
 (maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio3 pio4
 DMA modes:  mdma0 mdma1 mdma2
 UDMA modes: udma0 udma1 *udma2
 AdvancedPM=no
 Drive conforms to: device does not report version:

 * signifies the current active mode