misc/120406: Handling newly attached pcm devices (eg. via uaudio)

[Aragon Gouveia]

>Number:         120406
>Category:       misc
>Synopsis:       Handling newly attached pcm devices (eg. via uaudio)
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Fri Feb 08 10:10:00 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Aragon Gouveia
>Release:        7.0-RC1
>Organization:
>Environment:
FreeBSD geek.pcs.intranet 7.0-RC1 FreeBSD 7.0-RC1 #0: Wed Jan 16 17:07:28 SAST 2008     root at geek.pcs.intranet:/usr/obj/usr/src/sys/GEEK  i386
>Description:
On my FreeBSD workstations I frequently use a USB sound device (headphone amplifier).  I typically plug it in and out only when I need it, and expect (or hope!) for my system to use it when it's plugged in, but use the onboard sound when it is unplugged.

On FreeBSD 7 I used to set hw.snd.default_unit to 1 (from 0) after plugging the device in and then set the mixer levels to how I want them.  I've subsequently automated this ala devd and a shell script to do precisely the same thing, except the shell script also calls /etc/rc.d/mixer to restore the saved mixer settings in /var/db. I would like to PR my work in the hope of someone committing it as I think it might be useful to others.

I've included a devd.conf addition and an rc script for inclusion to /etc/rc.d.  The rc script only works if pcm_defaulthot is set to YES in /etc/rc.conf, and I would say it should be set to NO by default.

>How-To-Repeat:

>Fix:
devd.conf entry:

attach 100 {
	device-name "pcm[0-9]+";
	action "/etc/rc.d/pcm start $device-name";
};


Patch attached with submission follows:

#!/bin/sh
#

# PROVIDE: pcm
# REQUIRE: DAEMON cleanvar
# KEYWORD: nojail

. /etc/rc.subr

name=pcm
rcvar="pcm_defaulthot"
start_cmd="pcm_start"

load_rc_config $name

pcm_start()
{
	local pcm_unit
	
	pcm_unit=${pcm_device#pcm}
	if [ "${pcm_unit}" -ge 0 ]; then
		sysctl -w hw.snd.default_unit=${pcm_unit}
		/etc/rc.d/mixer start mixer${pcm_unit}
	fi
}

if [ -n "$2" ]; then
	pcm_device=$2
	run_rc_command $*
fi


>Release-Note:
>Audit-Trail:
>Unformatted: