[alsa-devel] user space control app driver interface for sound soc

Mark Brown broonie at opensource.wolfsonmicro.com
Fri Oct 1 01:34:55 CEST 2010

On Thu, Sep 30, 2010 at 04:10:15PM -0700, Peter Hsiang wrote:
> On Thu, Sep 30, 2010, Mark Brown wrote:

> > For these it depends; frequently these are (like your existing EQ
> > configuration) included in platform data but it really depends on how
> > they are generated and if they are custom to a particular system (eg,
> > dependant on plastics or particular speakers).

> In addition to the platform data, I would like in the future be
> able to load in data values that are stored in or generated from the
> user space.  Would I use the ALSA interface for this, or would it
> need to be a separate interface?

This would not be idiomatic for ALSA.  The particular interface to use
would depend on the volume of data being configured and the format it is
provided in.  If this is just for test and development purposes then
adding something to debugfs would be the normal thing.

> > > binary code image that goes into the chip's memory.

> > For this use request_firmware() and associated interfaces.

> Is it more common to load the firmware from the kernel space?
> Is there an established mechanism for loading from user space?

Have you looked at request_firmware()?  It is the established mechanism
for doing this and supports both firmware images built into the kernel
and firmware loaded from userspace, though firmware in userspace is the
more common approach.

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