Quaternary MI2S


#1

Hello,

I am using DragonBoard with Android OS. I would like to use the I2S pins of the low speed connector with the Quaternary MI2S interface to do both playback and capture in slave mode.

I read the “Enabling LS-I2S on Dragonboard 410c” guide and change the apq8016-sbd.dtsi files to add LS-I2S gpio pins to quaternary interfaces like this

	pinctrl-6 = <&ext_cdc_tlmm_lines_act &cdc_pdm_lines_act
					&cross_conn_det_act &cdc_ext_pa_act>;
	pinctrl-7 = <&ext_cdc_tlmm_lines_sus &cdc_pdm_lines_sus
					&cross_conn_det_sus &cdc_ext_pa_sus>;

But I still have no data getting out neither GPIO114 or GPIO 115 when using tinyplay command.

I have trouble to understand the Mux1 and Mux2 I2S notions. So I guess there is some configurations to make in the audio machine to use quaternary MI2S with low speed connector ?

For information, I checked all my clocks lines on scope and they are fine.

Thanks for your help !


#2

Which one, the Qualcomm version or the nearly AOSP one?

It’s always a good idea to link to whatever documentation you have been following rather than just name it. However if you are reading the document I think you are then it is aimed primarily at the Debian release (it should also apply to the nearly-AOSP code base but you may need some userspace changes to stop it trying to sent out audio via HDMI).


#3

Hi danielt,

Sorry for the missing info.

I use the Android BSP vLA.BR.1.2.7-01010-8x16.0-4 that I downloaded here:
https://developer.qualcomm.com/hardware/dragonboard-410c/software

The documention I mentionned can be found here:

The kernel of the documention is indeed a Debian one, but it is similar to the kernel I have on the Android and provide good help understanding how I2S is working on the DragonBoard.

I will try to look at the HDMI paths and turn it off to see if it helps re-routing audio to the low-speed connector.