Re: sysfs & ALSA card

From: Jaroslav Kysela
Date: Mon Oct 09 2006 - 02:29:13 EST


On Sat, 7 Oct 2006, Kay Sievers wrote:

> On Sat, Oct 07, 2006 at 02:55:31PM +0200, Kay Sievers wrote:
> > On Sat, 2006-10-07 at 00:44 -0700, Greg KH wrote:
> > > $ tree /sys/class/sound/
> > > /sys/class/sound/
> > > |-- Audigy2 -> ../../devices/pci0000:00/0000:00:1e.0/0000:06:0d.0/Audigy2
> > > |-- admmidi1 -> ../../devices/pci0000:00/0000:00:1e.0/0000:06:0d.0/Audigy2/admmidi1
>
> > > Yeah, I picked the wrong name for the card, it should be "card1" instead
> > > of "Audigy2" here, but you get the idea.
> >
> > That looks nice. Yeah, it should something that matches to the C1 in the
> > other names.
>
> This works fine for me with two soundcards and connect/disconnect
> module load/unload.
>
> All devices are in a flat list in the class directory, also the card%i
> ones:
> $ tree /sys/class/sound/
> /sys/class/sound/
> |-- adsp -> ../../devices/pci0000:00/0000:00:1e.2/card0/adsp

....

> In the /sys/devices hierarchy all devices belonging to the same card are
> nicely below the card device:
> $ ls -l /sys/devices/pci0000:00/0000:00:1e.2/card0
> total 0
> drwxr-xr-x 3 root root 0 2006-10-07 21:09 0-0:AD1981B
> drwxr-xr-x 3 root root 0 2006-10-07 21:09 adsp
> drwxr-xr-x 3 root root 0 2006-10-07 21:09 audio

....

The implementation looks good (Acked-by: Jaroslav Kysela <perex@xxxxxxx>).
Please, fix this small typo:

> --- linux-2.6.orig/sound/core/sound.c
> +++ linux-2.6/sound/core/sound.c
> @@ -268,11 +268,10 @@ int snd_register_device(int type, struct
> snd_minors[minor] = preg;
> if (card)
> device = card->dev;
> - preg->class_dev = class_device_create(sound_class, NULL,
> - MKDEV(major, minor),
> - device, "%s", name);
> - if (preg->class_dev)
> - class_set_devdata(preg->class_dev, private_data);
> + preg->dev = device_create(sound_class, device, MKDEV(major, minor),
> + "%s", name);
> + if (preg->dev)
> + dev_get_drvdata(preg->dev);

I think, it should be:

if (preg->dev)
dev_set_drvdata(preg->dev, private_data);

Jaroslav

-----
Jaroslav Kysela <perex@xxxxxxx>
Linux Kernel Sound Maintainer
ALSA Project, SUSE Labs
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