PATCH: creating devices for multiple sound cards

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

@@ -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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