Our device stopped working in dma mode in vista. This is our own device, and
we only did SCSI pass through commands to it. Under vista, these scsi pass
through commands only happen in PIO modes, not dma modes. In the device
manager the box is checked to use dma, and the device manager properly
reports the device as being in UDMA mode 2. However all transfers happen in
PIO mode which is too slow.

There appear to registry keys related to this, DeviceTimingMode. This is
different from the MasterDeviceTimingMode keywords in XP and Win2k.

QUESTION: How can I get Vista to do IOCTL_SCSI_PASS_THROUGH_DIRECT
DeviceIOControl ATAPI packet commands in DMA mode?

Are there different registry entries to control this?