On 11/11/2015 01:59 PM, Ricard Wanderlof wrote:
On Wed, 11 Nov 2015, Felipe Ferreri Tonello wrote:
But that is precisely the problem. The framework that manages the insertion and deletion of modules notes that my module has a usage count that is > 0 (in my case it is 2, which I'm convinced is because the card has been registered with ALSA), and refuses to free the module. So there is now way any unregister_card call can be made when my module is freed, as due to the usage count it would never even be attempted.
Do you mean that unbind is never called? Well, the framework should call bind/unbind for each user of your module.
Ok, I didn't know that. It's the first time I've been writing an ALSA driver as a loadable module.
How is your architecture? If you use one card for each probe of module then each bind should create one device, right?
In this case, it is a device which is located on the SoC. There is only one instance of it. When the module is loaded, it loads a codec driver with its associated DAI driver, a PCM driver, snd-soc-dummy-dai, and then a machine driver to tie it all together, finally registering the card with ALSA.
Looking in /sys/bus/platform/devices, there seems to be one device created for the codec itself, and one for the machine driver. I don't know if that's right or wrong, the ALSA driver hierarchy works in the sense that I can capture audio from it anyway.
Which one is the module you can't unload? The module that contains the machine driver should only have its reference count increment when a playback or capture stream is active so you can't remove it when it is actively in use.
- Lars