TLV320AIC3107: Setting Mic Bias

Hi,

Changing the MICBIAS level is through I2C register, below is the register address and value.

Regards.

He,

That would be the case if you are not using Linux and the driver.
The driver keeps the I2C bus busy so you can't communicate over the bus with i2c command.

I have to use the amixer controls (ALSA), but there is not control for the MICBIAS

Can you modify the register and reload?

Hi Luc,

You can set MICBIAS in firmware or DTS.

The MICBIAS code is below in tlv320aic31xx.c file:

fwnode_property_read_u32(aic31xx->dev->fwnode, "ai31xx-micbias-vg",
				 &micbias_value);
	switch (micbias_value) {
	case MICBIAS_2_0V:
	case MICBIAS_2_5V:
	case MICBIAS_AVDDV:
		aic31xx->micbias_vg = micbias_value;
		break;

Hi Raphael,

I noticed this as well, but I do not know how to toggle the MICBIAS during operationg.

All other functions have a name in the ALSA which can be toggled, but MICBIAS does not have on in the amixer controls.

Hi Luc,it's a command sample for your reference.

i2cset -y -f 2 0x4c 0x11 0x00 

It means to set I2C bus 2 at device 0x4C address and register 0x11 to 0x00

if you want to run 2 command at the same time,you can use:

i2cset -y -f 2 0x4c 0x11 0x00 & i2cget -y -f 2 0x4c 0x19

It means to set I2C bus 2 at device 0x4C address and register 0x11 to 0x00,and gets I2C bus 2 at device 0x4C address and register 0x19 at the same time.

"&" is the key word to run 2 command.

Hi Raphael,

This is indeed how to do it without a Linux driver.

The Linux ALSA prevents us from writing commands like i2cset or i2cget.
Instead we have to use: amixer cset name="name in driver"

These names are in the driver for example: amixer cset name="HP DAC Playback Volume"
The combination of the .c and the .h expains the register control.

Unfortunately these is no name to change the MICBIAS as far as I can see.

Hi Luc,

Just to let you know it's Chinese New Year break for the team in China, so it will be next week before Raphael can get back to you.

Regards.

Hi Luc,

You can add code in function hw_params to set MICBIAS.

Hi Peter,

Can you share the MICBIAS registers address and value?

MICBIAS is at page 0 register 25 and I believe Luc needs to set the value for the different input.

Hi Luc,

Let us know if the suggestion above by Raphael works for you.

I will look in to this.

Thanks.