atapicam + MO drive weirdness in 6.0

[Jason Harmening]

On my amd64 desktop, I have a Fujitsu DynaMO 2.3G ATAPI MO drive, and 
I've always had to use atapicam with it because there's no native ATA 
driver. The drive is genuinely capable of UDMA33, and I have 
hw.ata.atapi_dma turned on. In the past (with 5.x) the SCSI device listing 
that comes from atapicam at boot time has always shown the full transfer 
rate, as follows: 
 
da0 at ata0 bus 0 target 0 lun 0 
da0: <FUJITSU MCJ3230AP 0030> Removable Optical SCSI-4 device 
da0: 33.000MB/s transfers 
 
But since I upgraded to 6.0-BETA a month and a half ago, it doesn't look as if 
DMA is being enabled: 
 
da0 at ata0 bus 0 target 0 lun 0 
da0: <FUJITSU MCJ3230AP 0030> Removable Optical SCSI-4 device 
da0: 3.300MB/s transfers 

My UDMA33 CD burner still shows 33 MB/s in its atapicam SCSI listing, so I 
know UDMA transfers aren't completely broken with atapicam. And I can't 
seem to use atacontrol to manually change the transfer mode, because 
atacontrol has changed and requires an actual ata device file, as opposed to 
the old "atacontrol <channel#> <mode0> <mode1>" syntax. I can still use the 
MO drive, but I'd like to be able to tap into its full transfer rate.

I'm running the latest BETA4 now, and the problem is still present.  It's not 
a showstopper for me by any means, but both this problem and the removal of 
the old manual atacontrol syntax seem to be unfortunate regressions in the 
new ATA subsystem.

Any help or further explanation would be greatly appreciated.

Thanks,
Jason Harmening