[linux-audio-user] Hot(un)plug

[Frank Pirrone]

Frank Barknecht wrote:

>Hallo,
>Tim Hall hat gesagt: // Tim Hall wrote:
>
>  
>
>>hotplug is also involved in a chain of dependencies, which go:
>>hotplug <-ezusbmidi<-demudi-midi<-demudi-soundapps.
>>I'm hoping the last two are 'empty' packages, but I'm wary, because the ONE 
>>thing I DO want (and what got me into this mess in the first place) is to be 
>>able to fire up an external synth. 
>>firewire, usb & pcmcia I can do without.
>>I'm being double cautious due to the number of times I've lost the function I 
>>needed due to deleting something that seemed irrelevant. 
>>    
>>
>
>Be a little but careful here. demudi-midi and demudi-soundapps are so
>called tasks, IIR, they are itself empty, but depend on other
>packages to fulfill a task like "midi software in general". So I think
>it might be okay to remove them (try "apt-get -s remove hotplug"
>first), but YMMV. 
>
>I don't quite see why you *want* to remove hotplug. I see a lot of
>harmless warning messages on startup. That's perfectly normal on
>Linux. 
>
>ciao
>  
>
Just a comment on hotplug:  I was receiving an error when ALSA started 
up indicating that the driver was already running, and there indeed were 
some modules loaded, but not the snd-cs4236 and its support modules.  I 
had to do "service alsasound restart" to get the sound card/chip running.

What was happening was the modules.conf statement "alias usb-controller 
uhci" was causing my Midisport 2x2 to initialize, and have its firmware 
downloaded by ezusbmidi.  Without this line, the box lay dormant, but 
with it some ALSA modules were loading prematurely.

So, here's the point and the solution:  The file /etc/hotplug/blacklist 
is to allow hotplug to recognize and even initialize USB (and other 
busses) devices without loading the blacklisted modules yet.  These 
modules will be loaded later in the boot process (when alsasound 
executes for example) that will do the job at the proper time.

In my case listing the modules that loaded when Midisport 2x2 fired up, 
held them in check until alsasound was ready to load the entire suite of 
sound support modules for all devices.

Moral of the story:  Hotplug is valuable and powerful (I can 
disconnect/reconnect my UBS midi interface, scanner, and minidisk 
interface as seamlessly as Windoze) and its behavior can be easily 
controlled by the scripts and config files in /etc/hotplug.

Frank