[ltp] Re: T20 and floppy/cdrom swapping

[linux-thinkpad@linux-thinkpad.org]

On Wed, 11 Aug 2004, Paul Ionescu wrote:

> Hi Martin,
> 
> Is DMA working on your devices after hot-swapping ?
> Mine is not.

A timely question: I'm hotswapping (using a variety of idectl
commands, hdparm commands and finally settle on the "hotswap" package
itself) on my T40, and DMA disappears after the swap, no matter what
the device.  Currently swapping between a hard drive and DVD drive in
the Ultrabay Slim.  I see this is well-documented as a feature on
various lists, but no solution is forthcoming.  Has anyone got this
working?

Here's an example of the problem:

http://www.ussg.iu.edu/hypermail/linux/kernel/0402.0/1495.html

Alan Cox suggests here that hdparm -b0 might help, but my T40 won't
let me do that: "HDIO_SET_BUSSTATE failed: Operation not supported".

I mailed the originator of this thread, but he's found no solution.

My config:
T40/2.6.8-pre2 kernel with most recent ACPI patches running Fedora
Core 2

> BTW. If you use ACPI, you don't need to suspend the T20 to get the device
> out.

Confirmed here: ACPI at least stops the annoying beeping when you
remove a device and lets you swap "hot".  But I need DMA.  Anyone?