[Gta04-owner] /dev/ttyHS3 renames after resume to /dev/ttyHS6

NeilBrown neilb at suse.de
Fri Feb 10 22:14:05 CET 2012


On Fri, 10 Feb 2012 15:46:36 +0100 Radek Polak <psonek2 at seznam.cz> wrote:

> Hi,
> i found a problem with modem serial device. Probably after suspend/resume the 
> device node is renamed from /dev/ttyHS3->/dev/ttyHS6 and i cant send AT 
> commands then. Attached is dmesg output, you can search for ttyHS6 to find the 
> place.
> 
> These are all /dev/ttyHS before suspend:
> 	
> 	ttyHS0  ttyHS1  ttyHS2  ttyHS3  ttyHS4  ttyHS5
> 
> and this is how it looked after resume:
> 
> 	ttyHS0  ttyHS1  ttyHS2  ttyHS4  ttyHS5  ttyHS6
> 
> This is with kernel 3.2 and i have udev running on my system (could it be the 
> problem?)
> 
> Another question: i am always assuming /dev/ttyHS3 as modem device for AT 
> commands. Is it correct?

The best way to fix this is to create a udev rule that triggers when a tty is
created, reads the 'hsotype' attribute, and creates a stable link based on
that attribute.

Something like

SUBSYSTEM=="tty", ACTION=="add", KERNEL=="ttyHS*", ATTR{hsotype}=="?*", SYMLINK+="ttyHS_$attr{hsotype}"

Put that in /etc/udev/rules.d/hso.rules

and it should create named line
   /dev/ttyHS_modem
   /dev/ttyHS_gps
etc which are stable independent of the numbers assigned by the kernel.

Does this Option module really have a GPS in it?  If so, why aren't we using
it??

NeilBrown
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