Understanding udevinfo

Understanding udevinfo

[Richard A Downing FBCS]

I'm trying to get my usbs to work via udev.  And I'm finding it very hard to
understand udevinfo's -p option.  For instance:  In my /sys filesystem I have a
directory /sys/bus/usb/devices/1-2.  I have it in
/etc/udev/udev.rules as:

# The ov511 webcam
BUS="usb", PLACE="1-2", NAME="webcam%n"

and sure enough, in /udev I find a webcam0 with the correct major/minor.

If I type: 'udevinfo -p /sys/bus/usb/devices/1-2 -a' in an attempt to find out
what else I could put in udev.rules, all I get is:

# udevinfo -p /sys/bus/usb/devices/1-2 -a
couldn't get the class device

Other variations give similarly unhelpful results, so clearly I'm
misunderstanding the words:"sysfs device path used for query or chain."  I'm
assuming that path has it's usual Unix meaning.

Could someone give me an example or two?

-- 
Richard A Downing FBCS http://www.109bean.org.uk/
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Re: Understanding udevinfo

[Greg KH]

On Fri, Feb 20, 2004 at 10:38:58AM +0000, Richard A Downing FBCS wrote:
> I'm trying to get my usbs to work via udev.  And I'm finding it very hard to
> understand udevinfo's -p option.  For instance:  In my /sys filesystem I have a
> directory /sys/bus/usb/devices/1-2.  I have it in
> /etc/udev/udev.rules as:
> 
> # The ov511 webcam
> BUS="usb", PLACE="1-2", NAME="webcam%n"
> 
> and sure enough, in /udev I find a webcam0 with the correct major/minor.
> 
> If I type: 'udevinfo -p /sys/bus/usb/devices/1-2 -a' in an attempt to find out
> what else I could put in udev.rules, all I get is:
> 
> # udevinfo -p /sys/bus/usb/devices/1-2 -a
> couldn't get the class device

You need to use the /sys/class or /sys/block directory for udevinfo to
be able to give you anything that will work properly.

So for your example, try:
	udevinfo -p /sys/class/v4l/video0 -a

or whatever the class directory for your device is at.

Hope this helps,

greg k-h


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