snd_ctl_card_info
#define SNDRV_CTL_IOCTL_CARD_INFO _IOR('U', 0x01, struct snd_ctl_card_info)
return snd_ctl_card_info(card, ctl, cmd, argp);
struct snd_ctl_card_info *info __free(kfree) =
if (copy_to_user(arg, info, sizeof(struct snd_ctl_card_info)))
#define SNDRV_CTL_IOCTL_CARD_INFO _IOR('U', 0x01, struct snd_ctl_card_info)
err = snd_ctl_card_info(card_data->handle, card_data->info);
err = snd_ctl_card_info(handle, card_data->info);