[Alsa-devel] Alsa, devfs and multiples soundcards

[rtp]

        Hi,

Recently I switch to devfs (kernels 2.4.20 and 2.4.21). On Alsa loading, I
get this message :

kernel: devfs: devfs_register(unknown): could not append to parent, err:
-17

And all applications with oss were working with only one of my two
sound cards (ie gnome-volume-control). So I found this mail from T.Iwai on
lkml :

http://www.cs.helsinki.fi/linux/linux-kernel/2001-49/0266.html

So I've adapted this patch (modified patch joined with this mail) and all
works well.

Can somebody give me more informations about this ?


Arnaud Patard


diff -ur linux-2.4.21/drivers/sound/sound_core.c 
/usr/src/linux/drivers/sound/sound_core.c
--- linux-2.4.21/drivers/sound/sound_core.c     2001-09-30 21:26:08.000000000 +0200
+++ /usr/src/linux/drivers/sound/sound_core.c   2003-06-23 14:33:13.000000000 +0200
@@ -231,23 +231,29 @@
  
 int register_sound_special(struct file_operations *fops, int unit)
 {
-       char *name;
+       char *name, name_ext[32];
+       int suffix = 0;
+       
 
-       switch (unit) {
+       switch (unit & 15) {    
            case 0:
                name = "mixer";
+               suffix=1;
                break;
            case 1:
                name = "sequencer";
                break;
            case 2:
-               name = "midi00";
+               sprintf(name_ext, "midi0%d", unit / SOUND_STEP);
+               name = name_ext;
                break;
            case 3:
                name = "dsp";
+               suffix = 1;
                break;
            case 4:
                name = "audio";
+               suffix = 1;
                break;
            case 5:
                name = "unknown5";
@@ -263,26 +269,35 @@
                break;
            case 9:
                name = "dmmidi";
+               suffix = 1;
                break;
            case 10:
                name = "dmfm";
+               suffix = 1;
                break;
            case 11:
                name = "unknown11";
                break;
            case 12:
                name = "adsp";
+               suffix = 1;
                break;
            case 13:
                name = "amidi";
+               suffix = 1;
                break;
            case 14:
                name = "admmidi";
+               suffix = 1;
                break;
            default:
                name = "unknown";
                break;
        }
+       if (suffix && unit >= SOUND_STEP) {
+           sprintf(name_ext, "%s%d", name, unit / SOUND_STEP);
+           name = name_ext;
+       }
        return sound_insert_unit(&chains[unit&15], fops, -1, unit, unit+1,
                                 name, S_IRUSR | S_IWUSR);
 }