On 10/11/06, Bert Freudenberg <[EMAIL PROTECTED]> wrote:
The only documentation I could find is in a mailing list thread (http://mailman.laptop.org/pipermail/devel/2006-July/000672.html):*a- tell the EC to turn on MIC_AC (ie: bypass C35 and R25) [ OLPC specific ] *b- tell ALSA to disable VREFOUT and the high pass filter [ AD1888 specific ] So how do I "tell the EC to turn off MIC_AC"?
By default, ALSA AD1888 sets things into the appropriate mode for standard mics. You won't need to affect those mixer controls for regular mics. That is, VREFOUT is enabled, and the high pass filter is enabled. You asked a good question for users who want to use analog input mode, which is how do you tell the EC to turn off MIC_AC. For the A-Test board, Ray sent a sequence of IO read/writes that instruct the EC to turn off MIC_AC. I've pasted them here:
outp(0x381, 0xFC); outp(0x382, 0x10); mic_reg = inp(0x383); outp(0x381, 0xFC); outp(0x382, 0x10); outp(0x383, mic_reg | 0x40); // GPIO06 : bit6. 1: Enable output , 0: Disable Output ; outp(0x381, 0xFC); outp(0x382, 0x20); mic_reg1 = inp(0x383); outp(0x381, 0xFC); outp(0x382, 0x20); outp(0x383, mic_reg1 | 0x40); // GPIO06 : bit6. 1: high , 0: Low
Currently, I haven't figured out a clean way to expose the above EC functionality. Everyone is welcome to work on it and submit a patch. :-) Best regards, jaya _______________________________________________ Devel mailing list [email protected] http://mailman.laptop.org/mailman/listinfo/devel
