On Mon, 15 Nov 1999 08:15:41 -0800 
 Matt Thomas <matt@3am-software.com> wrote:

 > I noticed that the promise driver doesn't work when the device is in dma mode.
 > 
 > wd2: transfer error, downgrading to DMA mode 2
 > wd2(pciide2:1:0): using PIO mode 4, DMA mode 2 (using DMA data transfers)
 > wd2e: DMA error reading fsbn 9558208 of 9558208-9558223 (wd2 bn 29718208; cn 29482 tn 5 sn 37), retrying
 > pciide2:1:0: lost interrupt
 >          type: ata
 >          c_bcount: 8192
 >          c_skip: 0
 > pciide2:1:0: Bus-Master DMA error: missing interrupt, status=0x1
 > wd2: transfer error, downgrading to PIO mode 4
 > wd2(pciide2:1:0): using PIO mode 4

Really?  Works on my AlphaStation 200:

pciide0 at pci0 dev 13 function 0: Promise Ultra33/ATA Bus Master IDE Accelerator
pciide0: bus-master DMA support present
pciide0: primary channel configured to native-PCI mode
pciide0: using isa irq 10 for native-PCI interrupt
wd0 at pciide0 channel 0 drive 0: <IBM-DTTA-371440>
wd0: drive supports 16-sector pio transfers, lba addressing
wd0: 13783MB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 28229040 sectors
wd0: 32-bits data port
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2
wd0(pciide0:0:0): using PIO mode 4, Ultra-DMA mode 2 (using DMA data transfers)

...and it's my home directory and source tree on that machine.

        -- Jason R. Thorpe <thorpej@nas.nasa.gov>