Date:        Sat, 9 Feb 2002 17:37:18 +0100
    From:        Manuel Bouyer <bouyer@antioche.eu.org>
    Message-ID:  <20020209163718.GA1665@antioche.eu.org>

  | Promise PCI card doesn't support ATAPI devices properly (or at last I never
  | managed to get mine properly talk to my CD and ZIP).

When I got mine (first version) Promise certainly advised against using
ATAPI connected to it (haven't looked to see if they still do) .. but I
have a DVD out there, and under wintrash it works OK.

Under NetBSD it works OK as well - except it never seems to receive any
interrupts (or something similar), but doing something moderately intensive
to a regular IDE (ATA) drive connected to the same controller (I don't
have mine on the same channel) seems to cause enough interrupts to be
generated, and apparently the status indicates that the ATAPI device is
ready, as while this is happening NetBSD accesses the DVD drive out there
(to read CDs anyway, never tried dvdview or similar) just fine.

That is, my guess is that the atapi device isn't causing an IRQ to be
generated, but otherwise is acting as if it is done, with status
indicating that.   As long as something causes the controller to generate
an IRQ, the driver sees the ready ATAPI device and processes it.

Whether the wintrash driver knows some extra magic to get interrupts to
happen, or whether it simply sets up a high rate poll of the device, I
have no idea (wouldn't be surprised at the latter).

In any case, for me anyway, this is the only problem with ATAPI on the
promise - so when I happen to need to use it, I just start a
	find -mtime +0  /path/to/mounted/drive >/dev/null &
(in a loop usually - there's enough stuff out there that by the time it
has finished, all the early parts have gone from the caches, so it
actually keeps doing real I/O all the time).   This is a bit of an I/O cache
killer, but does mean the DVD drive works (I don't use it often under
NetBSD)

kre