At Tue, 08 Nov 2011 18:37:53 +0100, Clemens Ladisch wrote:
Takashi Iwai wrote:
Linus Torvalds wrote:
Takashi, any idea? Do we have some 8-sound-card limit somewhere?
I do see that we have that odd
if (card && card->number >= 8) return 0; /* ignore silently */in sound/core/sound_oss.c: snd_register_oss_device(), but it has no comments. The thing goes back to 2005 with the commit log entry of "[ALSA] dynamic minors (6/6): increase maximum number of sound cards", but the value '8'isn't explained.
ALSA itself can support 32 cards when CONFIG_SND_DYNAMIC_MINORS is set ... The above code is, however, about OSS-emulation. And I guess it's just a left-over of the old static limitation.
Yes; I didn't change the limit in the OSS emulation because the minor number layout doesn't have space for all 32 cards, and extending the limit to 16 did not seem worth the effort for a 'legacy' interface.
Actually OSS could support up to 16 cards (in theory).
Below is an untested fix patch. Does it work?
Not without increasing SNDRV_OSS_MINORS, too:
Ah, good catch. Below is the revised patch.
Takashi
--- From: Takashi Iwai tiwai@suse.de Subject: [PATCH] ALSA: Fix the card number limit of OSS-emulation
There are left-over codes from the ancient days with the static device number limitation of 8. Actaully OSS can support up to 16 cards.
Signed-off-by: Takashi Iwai tiwai@suse.de --- v2: fix SNDRV_OSS_MINORS, too
sound/core/sound_oss.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/sound/core/sound_oss.c b/sound/core/sound_oss.c index c700920..e952833 100644 --- a/sound/core/sound_oss.c +++ b/sound/core/sound_oss.c @@ -35,7 +35,7 @@ #include <linux/sound.h> #include <linux/mutex.h>
-#define SNDRV_OSS_MINORS 128 +#define SNDRV_OSS_MINORS 256
static struct snd_minor *snd_oss_minors[SNDRV_OSS_MINORS]; static DEFINE_MUTEX(sound_oss_mutex); @@ -111,7 +111,7 @@ int snd_register_oss_device(int type, struct snd_card *card, int dev, int register1 = -1, register2 = -1; struct device *carddev = snd_card_get_device_link(card);
- if (card && card->number >= 8) + if (card && card->number >= SNDRV_MINOR_OSS_DEVICES) return 0; /* ignore silently */ if (minor < 0) return minor; @@ -170,7 +170,7 @@ int snd_unregister_oss_device(int type, struct snd_card *card, int dev) int track2 = -1; struct snd_minor *mptr;
- if (card && card->number >= 8) + if (card && card->number >= SNDRV_MINOR_OSS_DEVICES) return 0; if (minor < 0) return minor;