John Gilmore wrote: >> Basically, for each configuration (external microphone plugged in, and >> external microphone not plugged in), I'd like to know the following: >> - which of the 8 microphones is the one to use >> - which ports we can turn off >> > > In reading the generic Intel HDA codec spec, and comparing it to the > http://dev.laptop.org/~dsd/20090629/codec0.txt, it seems that the > "Configuration Default" registers aren't being set up properly by OFW. >
That is correct. Patches welcome... > These registers define the physical location, color, and type of > device connected by motherboard wiring to each pin on the codec. > E.g. "Internal Mic Inside Lid" versus "External Green Headphone Output > 1/8" Jack on Left side". It's also easy to specify "Not Connected" > here. Normally these would be set at power-on by the BIOS, and then > read by the software in order to properly label the various audio > controls. This design avoids needing separate software driver mods > (kernel "quirks") for every single model of motherboard or laptop. > (These register contents are not retained over a full codec > power-down, so the kernel would probably want to save a copy from boot > time.) > > I hope you'll test with both mono and stereo external microphones. > The new hardware supports analog stereo input (and mic). It'd be a > shame to turn that capability off in software because it was only > tested with an analog mic. > > I think it should be possible to turn the mic bias on and off in > software (allowing the mic port to be used as "Line In"). > > It should be possible to turn the headphone output into an unamplified > Line Out. > > Testing the OLPC-specific analog "sensor" input mode would be very > useful. Given the stereo input jack, this would give experimenters > TWO analog inputs. (Somebody should tell XXX who's uploading > a bunch of instructions for making analog sensors on the wiki; > e.g. XXX). > > It would also be useful to test the higher sample rates and larger > sample sizes (24-bit samples, at 192 ksamples/sec outbound or 96 > ksamples/sec inbound). I've had trouble with those settings on an > Acer netbook, for example. > > If the microphone LED is on a GPIO under software control, independent > of the hardware's actual ability to listen on the internal mic, then > the LED isn't providing any useful function. (In which case that LED > hole might as well be used for sensing the brightness of the light > falling on the screen; one of the audio ADC's might be useful for > that.) > > John > _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
