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Re: usb vs. drivers

Hi Andrea,
I am using hotplug and udev. Thanks for the Gnome tips; I'd still like to solve this at a lower level if possible.
Do you know the process by which the system goes from (a) discovering that a device was connected to a USB port, to (z) binding a driver to that device?
The reason I'm asking is that I'm trying to make my camera work on Sarge. I *suspect* that no driver is getting loaded for it. I figure that understanding the process by which drivers get bound to hotplugged devices will let me better debug the problem. 

Thanks for your help,
Christian


Andrea Vettorello wrote:

On Tue, 30 Nov 2004 08:44:57 -0500, Christian Convey
<conveycj@npt.nuwc.navy.mil> wrote:


Hey guys,

I've got a usb camera (Kodak DX6490). I'm starting to suspect from
various tinkering I've done (in Knoppix, FC3, and Sarge) that the kernel
can't find a module to associate with the camera, and that's causing my
problems.

In 2.6/Sarge...
- How does the kernel know which driver to use for a USB device I plug in?




The kernel alone do nothing, you need "userland" programs to load
kernel modules when a new HD is plugged, like the "hotplug" package.

If you only need to access the photos, usually you only need to load
the "usb-storage" kernel module and maybe the "fat" or "vfat".

If you use Gnome, and you install "udev", "hal",
"gnome-volume-manager" and "hotplug", you usually end with a nice icon
on the desktop automagically whenever you attach a USB mass storage to
your pc, and digital cameras can be seen like USB mass storage.



- What's the easiest reliable way of knowing whether or not the kernel
managed to bind a driver to a USB device I plug in?




Looking in your /varl/log/syslog or perusing your /proc/bus/usb or
/sys/bus/sys. There are utilities that do this for you and show a nice
tree with device informations.


Andrea




--
Christian Convey
Computer Scientist,
Naval Undersea Warfare Center
Newport, RI
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