udev does not create ttyUSB devices for Visor

udev does not create ttyUSB devices for Visor

[Grischa Stegemann]

I have a Handspring Visor device which is supposed to communicate with my  
computer using the usb-serial driver.  
  
My udev version is 056 (Debian stable, Kernel 2.6.15.1) and it fails to 
create the appropriate device nodes ttyUSB0 and ttyUSB1. When I hit the  
hotsync-button on the cradle the kernel recognizes the device correctly:  
  
localhost kernel: usb 1-2: Handspring Visor now attached to ttyUSB0  
localhost kernel: usb 1-2: Handspring Visor now attached to ttyUSB1  
  
The simple udev-rule  
KERNEL="ttyUSB[0-9]*", NAME="%k"  
should now yield the corresponding devices, but it does not. It is  
perfectly ignored by udev and I cannot figure out why. There's no problem  
with any other device.  
  
It becomes even weirder (for me) if I create the device-nodes by hand:  
  mknod /dev/ttyUSB0 c 188 0; mknod /dev/ttyUSB1 c 188 1  
  
Now I can communicate with my Visor. BUT once the hotsync-procedure is  
finished, the visor disconnects completely from the computer, the  
usb-driver deregisters the device and -guess what!- NOW udev removes the  
corresponding ttyUSB-nodes.:(  
  
How comes udev is ignoring the device during registering but removes the  
device nodes during deregistering the device?   
It also removes them if I have absolutely no rule concerning ttyUSB  
at all.  
  
Any suggestion and/or clarification is greatly appretiated.  
  
Grischa  
 

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Re: udev does not create ttyUSB devices for Visor

[Kay Sievers]

On Tue, Mar 07, 2006 at 11:13:40PM +0100, Grischa Stegemann wrote:
> I have a Handspring Visor device which is supposed to communicate with my  
> computer using the usb-serial driver.  
>   
> My udev version is 056 (Debian stable, Kernel 2.6.15.1) and it fails to 
> create the appropriate device nodes ttyUSB0 and ttyUSB1. When I hit the  
> hotsync-button on the cradle the kernel recognizes the device correctly:  

You may need a newer udev version for a recent kernel, don't know if
that udev release still works correctly.

> localhost kernel: usb 1-2: Handspring Visor now attached to ttyUSB0  
> localhost kernel: usb 1-2: Handspring Visor now attached to ttyUSB1  
>   
> The simple udev-rule  
> KERNEL="ttyUSB[0-9]*", NAME="%k"  
> should now yield the corresponding devices, but it does not. It is  
> perfectly ignored by udev and I cannot figure out why. There's no problem  
> with any other device.  

It may be that some other rules catch away the event?

> It becomes even weirder (for me) if I create the device-nodes by hand:  
>   mknod /dev/ttyUSB0 c 188 0; mknod /dev/ttyUSB1 c 188 1  
>   
> Now I can communicate with my Visor. BUT once the hotsync-procedure is  
> finished, the visor disconnects completely from the computer, the  
> usb-driver deregisters the device and -guess what!- NOW udev removes the  
> corresponding ttyUSB-nodes.:(  

If the device node matches the kernel device that goes away, udev
removes the device node. That's the correct behavior.

> How comes udev is ignoring the device during registering but removes the  
> device nodes during deregistering the device?   
> It also removes them if I have absolutely no rule concerning ttyUSB  
> at all.  

There is no need to provide any rule if you only want a default device
node, udev will do that anyway.

Kay


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Re: udev does not create ttyUSB devices for Visor

[Greg KH]

On Tue, Mar 07, 2006 at 11:13:40PM +0100, Grischa Stegemann wrote:
> I have a Handspring Visor device which is supposed to communicate with my  
> computer using the usb-serial driver.  
>   
> My udev version is 056 (Debian stable, Kernel 2.6.15.1)

Please upgrade your udev version, as per the CHANGES file, it will not
work with that kernel version.

thanks,

greg k-h


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