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

			Jaroslav

...

From 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);
  

  if (IS_ERR(card->card_dev)) card->card_dev = NULL;

@@ -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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