[alsa-devel] [PATCH 1/5] allow up to 32 PCM devices

Jaroslav Kysela perex at perex.cz
Wed May 12 11:49:01 CEST 2010

On Wed, 12 May 2010, Takashi Iwai wrote:

> At Wed, 12 May 2010 09:29:57 +0200 (CEST),
> Jaroslav Kysela wrote:
>> On Wed, 12 May 2010, Wu Fengguang wrote:
>>> Reserve 32 minor numbers for PCM playback devices.
>>> The Intel SandyBridge HDMI audio codec provides 3 PCM devices with
>>> indices 3, 7, 8. Among which the device 8's minor number will be
>>> overlapped with the first capture device's minor number in the current
>>> static minor number allocation scheme.
>>> Also increase SNDRV_PCM_DEVICES to make pcm_dev_bits big enough to hold
>>> the increasing number of PCM devices.
>> I don't agree to have only 4 slots for soundcards in the static minor
>> numbering. Maybe the driver should be converted to use subdevices or we
>> might drop the static minor number allocation at all (it might have only
>> impact for old distros).
> Dropping such a base feature is really no good option.  Better to give
> simply an error for more than 8 PCMs in such a case, IMO.
> I also wonder whether having 4 individual PCMs is a way to go.  We may
> have PCM substreams, if any.  OTOH, the current IEC958 stream

Yes, I noted this above.

> assignment mechanism doesn't consider multiple substreams well, e.g.
> we have no proper way to match the IEC958 status bits control to a PCM
> substream.

We have subdevice member in snd_ctl_elem_id, so I don't see a problem.


Jaroslav Kysela <perex at perex.cz>
Linux Kernel Sound Maintainer
ALSA Project, Red Hat, Inc.

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