On Wed, Jun 13, 2001 at 10:20:03AM -0500, John Fulmer wrote:
> On Wed, 13 Jun 2001, Matthew Dharm wrote:
>
> > You generally need to get a device that works with linux. :)
> >
> > The SDDR-05 variants that can be supported are supported. The ones that
> > don't work can't be supported. At least, not without a _lot_ of effort,
> > including building a SCSI to ATA translation system.
>
> Could you explain this a bit to the non-developers? I take it this is a problem
> with newer USB storage devices, like my camera. What is the exact issue.
Actually, it's a problem with _older_ devices. Thus my lack of concern.
Most newer devices are spec-compliant with the USB Mass Storage
specification, and work out-of-the-box with the existing driver.
Basically, many early devices were actually IDE bridge chips located at the
end of a USB wire -- so the device needed to be sent very complex command
sequences to do register read/writes to the ATA controller, and then
exchange data.
Spec compliant devices have the command interpretation and execution
material built-in, so all we have to do is properly format the command and
send it, then exchange data, and check status. Even this isn't as easy as
it sounds.
AFAICT, the SDDR-05 line was retired in favor of the SDDR-31 line, which is
a spec-compliant device. At $30 (street) for an SDDR-31, I find it hard to
imagine that they will be keeping the -05 series around at all.
> And isn't the ide-scsi.o module a SCSI to ATA translator?
Nope. It takes SCSI requests off the bottom of the SCSI stack and pushes
them on to the top of the IDE stack. I need something that takes the
request off the SCSI stack and turns it into what comes out of the _bottom_
of the IDE stack. I've spoken to several people about this, including
IDE/ATA experts. Most people agree that it's (a) not easy and possibly not
really doable, and (b) just not worth it.
Matt
--
Matthew Dharm Home: [EMAIL PROTECTED]
Maintainer, Linux USB Mass Storage Driver
G: Baaap booop BAHHHP.
Mir: 9600 Baud?
Mik: No, no! 9600 goes baap booop, not booop bahhhp!
-- Greg, Miranda and Mike
User Friendly, 12/31/1998
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