diff options
| -rw-r--r-- | Documentation/sound/alsa/ALSA-Configuration.txt | 21 | ||||
| -rw-r--r-- | sound/core/init.c | 36 |
2 files changed, 56 insertions, 1 deletions
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt index 8e49c19f6c9..f34821d6d52 100644 --- a/Documentation/sound/alsa/ALSA-Configuration.txt +++ b/Documentation/sound/alsa/ALSA-Configuration.txt @@ -57,7 +57,9 @@ Prior to version 0.9.0rc4 options had a 'snd_' prefix. This was removed. - Default: 1 - For auto-loading more than one card, specify this option together with snd-card-X aliases. - + slots - Reserve the slot index for the given driver. + This option takes multiple strings. + See "Module Autoloading Support" section for details. Module snd-pcm-oss ------------------ @@ -2140,6 +2142,23 @@ alias sound-slot-1 snd-ens1371 In this example, the interwave card is always loaded as the first card (index 0) and ens1371 as the second (index 1). +Alternative (and new) way to fixate the slot assignment is to use +"slots" option of snd module. In the case above, specify like the +following: + +options snd slots=snd-interwave,snd-ens1371 + +Then, the first slot (#0) is reserved for snd-interwave driver, and +the second (#1) for snd-ens1371. You can omit index option in each +driver if slots option is used (although you can still have them at +the same time as long as they don't conflict). + +The slots option is especially useful for avoiding the possible +hot-plugging and the resultant slot conflict. For example, in the +case above again, the first two slots are already reserved. If any +other driver (e.g. snd-usb-audio) is loaded before snd-interwave or +snd-ens1371, it will be assigned to the third or later slot. + ALSA PCM devices to OSS devices mapping ======================================= diff --git a/sound/core/init.c b/sound/core/init.c index 2cb7099eb1e..48d38a79cbb 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -43,6 +43,40 @@ EXPORT_SYMBOL(snd_cards); static DEFINE_MUTEX(snd_card_mutex); +static char *slots[SNDRV_CARDS]; +module_param_array(slots, charp, NULL, 0444); +MODULE_PARM_DESC(slots, "Module names assigned to the slots."); + +/* return non-zero if the given index is already reserved for another + * module via slots option + */ +static int module_slot_mismatch(struct module *module, int idx) +{ +#ifdef MODULE + char *s1, *s2; + if (!module || !module->name || !slots[idx]) + return 0; + s1 = slots[idx]; + s2 = module->name; + /* compare module name strings + * hyphens are handled as equivalent with underscore + */ + for (;;) { + char c1 = *s1++; + char c2 = *s2++; + if (c1 == '-') + c1 = '_'; + if (c2 == '-') + c2 = '_'; + if (c1 != c2) + return 1; + if (!c1) + break; + } +#endif + return 0; +} + #if defined(CONFIG_SND_MIXER_OSS) || defined(CONFIG_SND_MIXER_OSS_MODULE) int (*snd_mixer_oss_notify_callback)(struct snd_card *card, int free_flag); EXPORT_SYMBOL(snd_mixer_oss_notify_callback); @@ -115,6 +149,8 @@ struct snd_card *snd_card_new(int idx, const char *xid, for (idx2 = 0; idx2 < SNDRV_CARDS; idx2++) /* idx == -1 == 0xffff means: take any free slot */ if (~snd_cards_lock & idx & 1<<idx2) { + if (module_slot_mismatch(module, idx2)) + continue; idx = idx2; if (idx >= snd_ecards_limit) snd_ecards_limit = idx + 1; |