From: Chris Rankin <rankinc@pacbell.net>
To: linux-sound@vger.kernel.org
Subject: PATCH: creating devices for multiple sound cards
Date: Sat, 14 Apr 2001 07:44:35 +0000 [thread overview]
Message-ID: <marc-linux-sound-98723432410017@msgid-missing> (raw)
Hi,
I have just installed a new sound card in my machine, and have left
the built-in sound chip enabled despite the motherboard manufacturer's
warning of Bad Things. The result is that I now have two sound devices
in my machine - an ICH (i810_audio) and a Soundblaster Live! The Live!
is device 0, of course. Anyway, I am using the ALSA drivers because
the native i810_audio module caused a kernel panic (NULL pointer
reference in an interrupt handler, I believe), and I have noticed that
the ALSA drivers have difficulty creating OSS device nodes for both
cards. I have traced the problem to the register_sound_special()
function within Linux's soundcore.o module. Basically, ALSA uses this
function to create OSS devices, but this function was never written
with more than one sound device in mind. Until now.
A few points about this patch:
1. I have renamed "sequencer2" to "music" because of a potential naming
conflict between devices 14,8 ("music" on card 0) and 14,33 ("sequencer"
on card 2).
2. I have renamed device "midi00" to "midi". "midi01" now becomes "midi1"
as well, although I would also point out that this is now consistent with
the behaviour of the register_sound_midi() function.
Having applied this patch, ALSA gives me two mixer devices in /dev/sound,
and I no longer get messages like these in my logs:
Apr 12 01:36:54 (none) kernel: devfs: devfs_register(): device already registered: "unknown"
Apr 12 01:40:04 (none) kernel: devfs: devfs_register(): device already registered: "mixer"
Apr 12 01:40:04 (none) kernel: devfs: devfs_register(): device already registered: "dsp"
Cheers,
Chris
--- linux-2.4.3/drivers/sound/sound_core.c.orig Fri Mar 16 23:00:44 2001
+++ linux-2.4.3/drivers/sound/sound_core.c Sat Apr 14 00:13:18 2001
@@ -227,9 +227,10 @@
int register_sound_special(struct file_operations *fops, int unit)
{
- char *name;
+ const char *name;
+ const int minor = (unit & 15);
- switch (unit) {
+ switch (minor) {
case 0:
name = "mixer";
break;
@@ -237,7 +238,7 @@
name = "sequencer";
break;
case 2:
- name = "midi00";
+ name = "midi";
break;
case 3:
name = "dsp";
@@ -255,7 +256,7 @@
name = "unknown7";
break;
case 8:
- name = "sequencer2";
+ name = "music";
break;
case 9:
name = "dmmidi";
@@ -279,7 +280,7 @@
name = "unknown";
break;
}
- return sound_insert_unit(&chains[unit&15], fops, -1, unit, unit+1,
+ return sound_insert_unit(&chains[minor], fops, -1, minor, minor+128,
name, S_IRUSR | S_IWUSR);
}
-
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