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@xxxxxxxx>
> 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@xxxxxxxx>
> ---
> 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@xxxxxxxx>
> Linux Kernel Sound Maintainer
> ALSA Project, Red Hat, Inc.
>
> _______________________________________________
> Alsa-devel mailing list
> Alsa-devel@xxxxxxxxxxxxxxxx
> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>
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