[alsa-devel] Dynamically registering a codec

Jon Smirl jonsmirl at gmail.com
Thu May 14 20:56:32 CEST 2009

On Thu, May 14, 2009 at 2:38 PM, Mark Brown
<broonie at opensource.wolfsonmicro.com> wrote:
> On Thu, May 14, 2009 at 01:57:37PM -0400, Jon Smirl wrote:
>> Now I see what you mean. I need to make the codec into a device so
>> that I can dynamically load and find it. On PowerPC the codecs don't
>> have to be compiled in, they can be on an initrd.
> This is the case for all platforms, it's not in any way PowerPC specific.
>>                                                   The code in
>> of_simple will find the right driver and get it into memory. The
>> platform device is what triggers the kernel to go searching for the
>> module on initrd.
> On every other platform the codec driver is linked to directly by the
> machine driver so loading the machine driver will also cause the codec
> driver to be loaded - at this stage of_simple isn't involved at all
> except in that it has removed the usual way of getting the codec driver
> loaded for AC97 devices.
>> This isn't platform specific, other platforms could implement this but
>> they don't have anything like a device tree telling them which modules
>> to load. A device tree is a probing mechanism for devices that can't
>> be probed.
> Other platforms use platform devices in just the same way, they just
> happen to set them up in a C file rather than a .dts file.  The
> mechanisms for loading things after that are identical.  What's PowerPC
> specific here is that you are trying to use this of-simple mechainsm and
> that's defeating the way this is handled for AC97 codec drivers.
> Please re-read my comments about the specific problems with AC97 - this
> is key here.

So I need to make fabric drivers for Efika and Phytec that statically
link to the respective AC97 codecs? And the core is going to get
updated so that I can remove these static links?

Jon Smirl
jonsmirl at gmail.com

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