Hi Ricard, On 11/11/15 12:59, 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. Well, this is not ALSA specific, it really depends on which framework your driver is based on, but they all share similar flow on probe and remove driver. > >> 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. > What exactly do you want? If it is driver that register and unregister cards based on the user interaction of probing and removing that module from user-space, then you are not looking for a driver. What you are looking for is just a kernel module. The only way of interacting with it is dealing with module_init and module_exit. On the other hand, if in fact you want a driver, then check sound/drivers/dummy.c for an example. You can also read the Documentation/driver-model/platform.txt for more info. -- Felipe
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