DMA is broken in 2.6.13.2 and opensuse 2.6.13-15, for  my  cdrom/dvd 
burner.

My chipset is:

00:0f.1 IDE interface: VIA Technologies, Inc. 
VT82C586A/B/VT82C686/A/B/VT823x/A/C/VT8235 PIPC Bus Master IDE (rev 06)

I have also heard ICH5 has this problem as well.

I can tell you that hdparm -iI /dev/hdb reports the drive in udma4 mode.

This drive is a: LITE-ON DVDRW SOHW-1693S, FwRev=KS09 However I think 
that maybe irrelevant.

On .13 I get this at the end of dmesg:

hdb: drive_cmd: status=0x51 { DriveReady SeekComplete Error }
hdb: drive_cmd: error=0x04 { AbortedCommand }
ide: failed opcode was: 0xec
hdb: drive_cmd: status=0x51 { DriveReady SeekComplete Error }
hdb: drive_cmd: error=0x04 { AbortedCommand }
ide: failed opcode was: 0xec

On .12 I get this but not on .13:

VP_IDE: VIA vt8237 (rev 00) IDE UDMA133 controller on pci0000:00:0f.1
    ide0: BM-DMA at 0xa000-0xa007, BIOS settings: hda:pio, hdb:DMA
    ide1: BM-DMA at 0xa008-0xa00f, BIOS settings: hdc:pio, hdd:pio



DMA was working correctly in 2.6.12


Attached is the .12 and .13 dmesg diff.