Hello,
I have a C-Media CMI8738 soundcard. I'm using it because it has a
special feature that I want: the OPL3 synth.
It creates two ALSA MIDI ports. In my case, these are '20:0, C-Media
CMI8738, C-Media CMI8738 MIDI' and '21:0, OPL3 FM synth, OPL3 FM Port'.
The first one is completely useless - this soundcard actually has no
game/midi port connector on it. The second one is what I really want.
The problem I have is that the first port has a weird problem in that if
you access it in some way (eg. play a midi file through it with
aplaymidi) it has a very high chance of making the computer reboot
suddenly and without warning. This seems to be different from a kernel
panic because my system is configured not to automatically reboot on
panic, and I don't get the capslock/scroll lock lights flashing - the
system just reboots suddenly and without warning.
I can't simply avoid using that MIDI port - music software I use, such
as Rosegarden, seems to automatically connect to all MIDI ports as part
of its initialisation routine. I discovered the problem because it was
happening (my system was unexpectedly rebooting) every few times I
opened a project file in Rosegarden.
So I'm looking for a workaround that will remove/destroy/eliminate this
unwanted and unused MIDI port so that nothing can make my system reboot
by accident. So far I have tried this:
* load snd_cmipci with parameter 'mpu_port=0'. This didn't work, the
unwanted port was still created and still caused the reboot when I
tested it.
* prevent snd_mpu401_uart from loading. This didn't work - snd_cmipci
refused to load without it.
Does anyone have any ideas or suggestions?
Maybe this is something that the ALSA driver developers should be made
aware of, but I thought I should ask about it here first.
Some details about this soundcard in case it's interesting or useful:
It's a PCIe card. These PCIe soundcards with the CMI8738 chipset are all
over ebay right now. I believe it's actually a PCI card with a PCIe
bridge/interface chip on it. Unlike most of the actual PCI sound cards
with this chipset, it has no game/midi connector/port on the back.
I have tested this with Linux kernels 3.16.0 and 5.3.0
Regards,
Patrick
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