Liam Girdwood wrote: >> I guess I just don't understand why the codec driver is acting like the "master" driver of >> ASOC. IMHO, the codec driver should be doing two things: > > I guess this is due to an ordering issue we had during early > development. We had to make sure that the I2C probe of the codec > succeeded before registering the card, pcms, etc. Fwiw, I do intend to > address this in future versions (I should probably add a road map to the > wiki now). In that case, I think we can solve this problem as well as the PowerPC device tree problem in one shot, because they're basically the same problem. Anyway, let me see if I get this right: 1. The first function called is eti_b1_init(). 2. eti_b1_init() calls platform_device_add() to add an soc-audio class device and register the eti_b1_snd_devdata structure. 3. The registration causes a number of things to happen, one of which is a call to soc_probe(). 4. soc_probe() sees that the snd_soc_machine_eti_b1.probe is NULL, so that part is skipped. 3. soc_probe() sees that snd_soc_machine_eti_b1.dai_link->cpu_dai->probe is also NULL, so that part is skipped. (eti_b1_snd_devdata.machine == snd_soc_machine_eti_b1) 4. soc_probe() sees that soc_codec_dev_wm8731.probe is not NULL, so it calls wm8731_probe(). 5. wm8731_probe() registers an I2C driver. 6. The I2C class driver calls wm8731_i2c_driver.attach_adapter, which is wm8731_i2c_attach(). 7. wm8731_i2c_attach() calls i2c_probe(), which in turn calls wm8731_codec_probe() 8. wm8731_codec_probe() allocates a snd_soc_codec structure. 8. wm8731_codec_probe() calls wm8731_init(). This means that if there is no I2C support, wm8731_init() will never be called. 9. wm8731_init() initializes the snd_soc_codec structure. Question: why doesn't wm8731_probe() initialize the non-I2C parts of the snd_soc_codec structure? For example, snd_soc_codec.dai, snd_soc_codec.name, and snd_soc_codec.owner? That way, the snd_soc_codec structure will be properly initialized even when there's no I2C. 10. wm8731_init() calls snd_soc_new_pcms. 11. wm8731_init() exits, wm8731_codec_probe() exits, wm8731_i2c_attach() exits, and then wm8731_probe() exits. Control returns to soc_probe(). 12. soc_probe() notices that eti_b1_snd_devdata.platform.probe is NULL, so it skips that. Question: why don't you define a function for at91_soc_platform.probe, and in that function you can call snd_soc_new_pcms()? That way, you guarantee the codec driver's I2C interface is initialized before snd_soc_new_pcms() is called, and you avoid have PCM calls in the codec driver. >> ASOC and the machine driver should then work in tandem to decide which driver will do what >> and which capabilities are *actually* supported. *Something* needs to look at the entire >> system and say to each device, "Well, yes, I know about this little feature of yours, but >> we're just not going to support that today." >> > > The machine driver pretty much already does this. It can override valid > hardware configurations and return -EINVAl if required. Do you have an example of that? Would that be eti_b1_hw_params()? -- Timur Tabi Linux Kernel Developer @ Freescale _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
