On 12/01/2017 07:30 AM, Mark Brown wrote: > On Wed, Nov 29, 2017 at 03:32:51PM -0600, Andrew F. Davis wrote: >> Leaving microphone bias off is a valid setting and even used in the DT >> binding document example. Add this setting here and document the same. > >> - ai31xx-micbias-vg - MicBias Voltage setting >> + 0 or MICBIAS_OFF - MICBIAS output is powered off >> 1 or MICBIAS_2_0V - MICBIAS output is powered to 2.0V >> 2 or MICBIAS_2_5V - MICBIAS output is powered to 2.5V >> 3 or MICBIAS_AVDD - MICBIAS output is connected to AVDD > > This doesn't make much sense. If we enable the microphone with a > voltage of 0V that's not going to work terribly well - I'd expect this > property to control the voltage set when it's enabled, not if it's > enabled. > I agree about this not making much sense, but I'm not sure the right way forward here. Personally I wouldn't have put MicBias voltage in DT to begin with, it is runtime configurable and depends on user runtime inserted microphone, not really a hardware description :/ The enable/disable is controlled by a DAPM and should be wired to enable whenever we are recording from the related microphone pin. So then without MICBIAS_OFF the user is forced to select from the above voltages whenever recording, which may not be correct if they are using a mic that doesn't need bias. The best option I think would be to drop this from DT, but I don't feel like fighting that battle right now. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
