Audio codec device tree entries

[Grant Likely]

On 10/24/07, Timur Tabi <timur at freescale.com> wrote:
> Grant Likely wrote:
>
> > Now is probably a good time to mention that there is *nothing* in the
> > device tree that enforces a 1:1 relationship between device tree nodes
> > and driver instances.  Sure, it make sense to register the i2s and
> > codec drivers from probing on the i2s and codec nodes.  However, there
> > is nothing that prevents the codec driver from *also* registering a
> > fabric driver based on a property in the codec node or the board-level
> > compatible property.
>
> Wouldn't it make more sense for the fabric driver to register the codec driver?
>   The fabric driver is the "master" of the other drivers, should it needs to
> load and run first.

It doesn't really matter.  There doesn't need to be a 1:1 relationship
between driver instances and device nodes.  A probe on one device node
can cause the instantiation of both a fabric driver and a codec driver
(just put the appropriate calls in the of_platform_bus probe hook).

>
> > Fabric drivers are codec specific anyway.
>
> Yes and no.  They're really platform-specific, but they should be able to scan
> the device tree, determine which codecs are actually on the system, and then
> link in the appropriate codec driver.

My point is; most likely if you change the codec, you need to change
the fabric driver too.

There will be many fabric drivers using a single codec,
but there will not be many codec drivers using a single fabric.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely at secretlab.ca
(403) 399-0195