USB scanner not attached when connected after system startup]

[Roland Smith]

On Mon, Jan 03, 2005 at 08:23:33PM +0100, Harald Weis wrote:
> On Sun, Jan 02, 2005 at 02:22:27PM +0100, Roland Smith wrote:
> > On Sun, Jan 02, 2005 at 01:17:37PM +0100, Harald Weis wrote:
> 
> > Sometimes the device that gets noticed by usbd is not the device that
> > you eventually want. For instance, I have a usb pendrive. When I plug it
> > in, usbd sees a device called umass0. But what I'm interested in is the
> > adXsY device that represents the partition on the drive. So in this case
> > usbd isn't very helpful.
>   
> and you would see it in dmesg ?

Yes. For instance when I plug in my digital camera to offload pictures,
I get the following in dmesg:

umass0: NIKON NIKON DSC D70, rev 1.10/1.00, addr 2
da0 at umass-sim0 bus 0 target 0 lun 0
da0: <NIKON D70 1.01> Removable Direct Access SCSI-2 device 
da0: 1.000MB/s transfers
da0: 244MB (500401 512 byte sectors: 64H 32S/T 244C)

In usbd I'd only see the events related to umass0.

> > I've asked this before, but you never answered; If you plug in the
> > scanner in a running system, do you see it in the 'dmesg' output?
> 
> No.

That's not good. AFAICT, the code that reports a new scanner to dmesg is
also present in 4.x, so if you don't see a message, it looks like the
scanner is not found for one reason or another.

Do you see anything in dmesg if it is available at boot? If so, it would
look like a definite bug to me. 

But since it works on 5.3, I don't know what the value would be of
sending a Problem Report on 4.9, since 5.3 is now STABLE.
Have you considered upgrading to 5.3?

> [Very sorry for not having replied to that question before. I have
> simply repressed it (verdrängt in German) 

:-)

> because sane, scanimage and
> last not least usbd clearly proved - to my troubled mind - that the
> scanner was not attached and I was subconsciously convinced that dmesg
> signals only events during system startup. This is how I used it up to
> now. I still don't know what `core file' and `name list' or `kernel
> image' exactly means.]

See 'man core' for more info about coredumps. Core is an old term for
memory (dating from the time of ferrite core memory). See the jargon file.

> > If you do _not_ get a message like:
> > 
> > uscanner0: EPSON EPSON Scanner, rev 1.10/3.02, addr 2
> > 
> > in your dmesg after you plug in the scanner, I'd say that your kernel
> > doesn't recognize the scanner for some reason. This would be a bug in 4.x.
> 
> So I've got a long-standing bug (on two different boxes and several
> releases starting in 2001) Very strange that I'd be the only case in
> this world. I couldn't find anything in the mailing list archives.

It might be the combination of the type of motherboard, chipset and
scanner that causes the problem. So you could get only a small number of
people affected. During a recent discussion of a bug in the direct
rendering code for Radeon graphics cards on amd64, only three users of those
particular cards on amd64 participated IIRC.

> > If it does appear, the scanner is found by the kernel. If the scanner
> > does not work in this case, what exactly is the reported error? If
> > you've not running devfs, and the scanner wasn't available at boot time,
> 
> devfs does not exist on 4.x

According to the manual page for devfs(5), it has existed since
2.0. AFAIK, it has only become mandatory in 5.x. 

> > maybe the the device node was never created? Can you confirm that the
> > device node for the scanner exists if you boot up without the scanner
> > present?
> 
> Yes, I confirm definitely.

Ok, so at least that's not the problem. :-)

Roland
-- 
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