Conflict between hotplug and sound on a laptop
The Problem : I installed LM8.2 on my Inspiron 5000e laptop which had LM8.0
running without problems. After installation the sound was not working. On
running harddrake, sound was getting configured but on a reboot it stopped
working again.
Analysis : So I sat down to analyze what was exactly happening. I found that
the OSS sound driver "maestro" was being used by default and after loading
the driver, the sound was fine. To trace what happened after reboot, I checked
the list of modules loaded after booting. Surprisingly I found snd-card-es1968
loaded with all the other standard alsa modules (minus the OSS emulation
modules). After looking at the log messages I found that hotplug was trying
to setup snd-card-es1968 and maestro drivers at bootup. So this sequence of
events was taking place:
hotplug does modprobe on snd-card-es1968 : the driver gets loaded
hotplug does modprobe on maestro : the driver is not loaded since a sound
driver is already loaded and card is in use
<after certain steps>
modprobe maestro (due to alias sound maestro in modules.conf). : The driver
cannot be loaded as sound card already in
use
Now I tried to find out from where hotplug gets the list of modules to load.
It turns out that hotplug uses "pcimodules" to get a list of modules
available for all of the PCI h/w and tries to load all modules!
Solution : This is indeed a temporary fix. I added both maestro and
snd-card-es1968 to /etc/hotplug/blacklist. This prevented them being
loaded at bootup by hotplug and thus "modprobe maestro" at the end of the
bootup process was able to start my sound! Later, I enabled alsa and got alsa
drivers successfully loaded at bootup.
I hope this problem is helpful to you guys. I wonder if all Mandrake laptop
users with alsa+oss drivers installed are encountering the same problem.
Regards,
Sarang
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sarang Lakare
Dept. of Computer Science, SUNY at Stony Brook
www : http://www.cs.sunysb.edu/~lsarang
linux : http://www.cs.sunysb.edu/~lsarang/linux
!!Join the fight for freedom - Go GNU/Linux!!
