At Tue, 11 Nov 2008 17:00:41 +0100 (CET), Jaroslav Kysela wrote:
Hi all,
based on discussion today, I prepared a patch to handle udev-style card renaming. Comments are welcome.
Looks good to me. The sanity check of the id string should be used for the assignment from the module option, too.
I first thought of making id module parameter writable. But, this would require more works, and needs to patch allover places.
One another solution regarding udev thingy is to accept a path as a card number/index in alsa-lib. When the card begins with '/', it's handled as a path, for example. Then, you can simply open that file instead of parsing the whole snd_card_get_index(), etc.
This is a bit hacikish, so I'm not fully convinced, though. Just an idea make the things without changing the kernel infrastructure.
thanks,
Takashi
JaroslavFrom b0dca2c114f465a11f1595854090a85f58870b35 Mon Sep 17 00:00:00 2001
From: Jaroslav Kysela perex@perex.cz Date: Tue, 11 Nov 2008 16:51:02 +0100 Subject: [PATCH] ALSA: add /sys/class/sound/card#/id (r/w) and card#/number (r/o) files
For udev, we need a way to rename soundcard names. The soundcard numbers (indexes) are hardwired but we have a text identification which can be changed at run-time. The ALSA user space tools already allow using of this text identification.
Signed-off-by: Jaroslav Kysela perex@perex.cz
sound/core/init.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 65 insertions(+), 1 deletions(-)
diff --git a/sound/core/init.c b/sound/core/init.c index b47ff8b..1426abd 100644 --- a/sound/core/init.c +++ b/sound/core/init.c @@ -533,6 +533,64 @@ static void choose_default_id(struct snd_card *card) } }
+#ifndef CONFIG_SYSFS_DEPRECATED +static ssize_t +card_id_show_attr(struct device *dev,
struct device_attribute *attr, char *buf)+{
- struct snd_card *card = dev_get_drvdata(dev);
- return snprintf(buf, PAGE_SIZE, "%s\n", card ? card->id : "(null)");
+}
+static ssize_t +card_id_store_attr(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)+{
- struct snd_card *card = dev_get_drvdata(dev);
- char buf1[sizeof(card->id)];
- size_t copy = count > sizeof(card->id) - 1 ?
sizeof(card->id) - 1 : count;- size_t idx;
- int c;
- for (idx = 0; idx < copy; idx++) {
c = buf[idx];if (!isalnum(c) && c != '_' && c != '-')return -EINVAL;- }
- memcpy(buf1, buf, copy);
- buf1[copy] = '\0';
- mutex_lock(&snd_card_mutex);
- if (!snd_info_check_reserved_words(buf1)) {
__exist:mutex_unlock(&snd_card_mutex);return -EEXIST;- }
- for (idx = 0; idx < snd_ecards_limit; idx++) {
if (snd_cards[idx] && !strcmp(snd_cards[idx]->id, buf1))goto __exist;- }
- strcpy(card->id, buf1);
- mutex_unlock(&snd_card_mutex);
- return count;
+}
+static struct device_attribute card_id_attrs =
- __ATTR(id, S_IRUGO | S_IWUSR, card_id_show_attr, card_id_store_attr);
+static ssize_t +card_number_show_attr(struct device *dev,
struct device_attribute *attr, char *buf)+{
- struct snd_card *card = dev_get_drvdata(dev);
- return snprintf(buf, PAGE_SIZE, "%i\n", card ? card->number : -1);
+}
+static struct device_attribute card_number_attrs =
- __ATTR(number, S_IRUGO, card_number_show_attr, NULL);
+#endif /* CONFIG_SYSFS_DEPRECATED */
/**
- snd_card_register - register the soundcard
- @card: soundcard structure
@@ -553,7 +611,7 @@ int snd_card_register(struct snd_card *card) #ifndef CONFIG_SYSFS_DEPRECATED if (!card->card_dev) { card->card_dev = device_create(sound_class, card->dev,
MKDEV(0, 0), NULL,
MKDEV(0, 0), card, "card%i", card->number);@@ -576,6 +634,12 @@ int snd_card_register(struct snd_card *card) if (snd_mixer_oss_notify_callback) snd_mixer_oss_notify_callback(card, SND_MIXER_OSS_NOTIFY_REGISTER); #endif +#ifndef CONFIG_SYSFS_DEPRECATED
- if (card->card_dev) {
device_create_file(card->card_dev, &card_id_attrs);device_create_file(card->card_dev, &card_number_attrs);- }
+#endif return 0; }
-- 1.6.0.1.217.gb4928
Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project, Red Hat, Inc.
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