Understanding dmesg output, and udevinfo...

nutnut · 05-13-2007, 12:29 PM

Hey,

Just trying to get my digital camera working here, and have come across a couple of things I don't really understand.

Code:

usb 1-6: new high speed USB device using ehci_hcd and address 9
usb 1-6: configuration #1 chosen from 1 choice

So, I believe ehci is USB 2.0, but what does address 9 specify. On the second line, where abouts are these configuration choices it speaks of, and what are they for?

By seeing that output, I was under the impression that the device was indeed connected in some respect, however I can't find the device in

Code:

udevinfo -a -p /sys/class/scsi_generic/sg0'

or as a noticeable device under /dev.

What else needs to be done for something more useful to happen?

For you reference, the device is a Canon Digital Ixus 65.

Any advice you could offer would be most appreciated.

Thanks in advance,
James

ilikejam · 05-13-2007, 01:57 PM

Hi.

I'm not too familiar with the details of how USB works on Linux, but it shouldn't matter.

You'll have to use gphoto2 (or more likely a front-end like gthumb) to get your photos off the camera. Canon cameras (at least their consumer efforts anyway) don't appear as storage devices, so you won't get an sgX device.

Dave

nutnut · 05-13-2007, 02:22 PM

Hey,

Ah, well I guess that makes more sense.

I'm using digiKam as my front end (KDE), however I'm not quite sure how to configure it to find my Canon (auto-discover doesn't find anything, and no luck selecting my particular camera model with default settings either).

When I have this camera connected to a Windows machine, it seems to go into a kinda disk mode - screen blacks out and the activity light illuminates.

Attached to my Linux machine however, the screen remains as it is during normal photo viewing mode, and the activity light remains off. Perhaps this is of no significance, but then again perhaps it is.

Do you know how I can interface with the camera if it doesn't create a device node for somewhere?

Kind regards,
James

ilikejam · 05-13-2007, 02:35 PM

Hi again.

Few things to try:
Make sure the camera is in 'play' mode.
Try running digiKam as root (could be a permissions issue).
Post the output from

Code:

gphoto2 --list-cameras | grep "Canon Digital IXUS 65"
gphoto2 --auto-detect

with the camera plugged in (and as root if you don't get anything as a normal user).

Dave

nutnut · 05-13-2007, 03:11 PM

Hi,

I ran digiKam as root as you suggested, and my Canon was auto-detected (woo!). No idea how to change the device permissions though.

gphoto2 doesn't have my camera in the list (only goes as far as the IXUS 60), and when I try and auto detect as non-root I get:

Code:

james@grapefruit ~ $ gphoto2 --auto-detect
Model                          Port
----------------------------------------------------------

And then as root:

Code:

grapefruit james # gphoto2 --auto-detect
Model                          Port
----------------------------------------------------------
PTP/IP Camera                  usb:
PTP/IP Camera                  usb:001,009

This output reflects that from digiKam when ran as root, and the specified 'usb:001,009' corisponds with:

Code:

usb 1-4: new high speed USB device using ehci_hcd and address 9

Thanks for your help thus far.

Kind regards,
James

ilikejam · 05-13-2007, 03:32 PM

On Fedora, the permissions are set up by a script which HAL calls when it sees the new camera device. I don't think this is set up in Gentoo. This page shows how it's done:
http://www.gphoto.org/doc/manual/permissions-usb.html
It's pretty horrific, though, as I'm sure you'll agree.

Probably easier just to do

Code:

find /dev/bus/usb -type c -cmin -2

just after you've plugged in the camera. This finds device nodes which have been changed in the last 2 minutes. Hopefully your camera should be the only device found. 'chown yourusername:root' the device found (as root), and you should be good to go.

Hopefully.

Dave

ilikejam · 05-13-2007, 03:37 PM

Actually, scratch that. The output from 'gphoto2 --auto-detect' tells you where the device is. e.g. /dev/bus/usb/001/009 from the output above (usb:001,009). Just 'chmod yourusername:root' that file, and you should be OK.

Dave

nutnut · 05-14-2007, 12:08 AM

Hey,

I had a quick look at the udev rule sets last night, as I had just had a brain wave, and I noticed '99-libgphoto2.rules'. Had a look inside, and sure enough there were rules there for lots of products from different vendors.

Upon examining the implications of these rules, and the interface /dev/bus/usb/001/xxx, it became apparent that my camera was indeed being detected and effected by them.

Turns out that the interface's group was set to 'plugdev' by udev, and that my non-root user wasn't in that group. I added myself to it, and hey presto I have access

!

Thanks for a big push in the right direction there, it probably would have taken me forever to figure this out otherwise :P.

Thanks again,
James