Kernel modifications for headless device


#1

Hi,

I am trying to build custom kernel for headless device.
I tried commenting out the display module in dts but that affected the audio playback/recording.

Please assist if there exists a document to help build for headless devices.

Regards.


#2

hi,

can you please be more specific:

  • which change are you doing in DTS?
  • which board are you running on?
  • what do you mean by audio playback/record? what specific use case?

also , are you loading/starting the DSP by any chance?


#3

Hi Nicolas,

Sorry for my ignorance as i am just getting to learn about kernel modifications.

I am trying to build a minimal image with audio support for analog and if possible I2s as well, for apq8016 based DB410 and eragon410.
In eragon I commented out the “mdss_dsi0” part from the dts posted at https://pastebin.com/FmvL2J0K.
The device booted fine but when i tried to enable microphone it gave me error

root@linaro-developer:~# amixer sset ‘RX1 MIX1 INP1’ 'RX1’
amixer: Unable to find simple control ‘RX1 MIX1 INP1’,0

root@linaro-developer:~# amixer sset ‘RX2 MIX1 INP1’ 'RX2’
amixer: Unable to find simple control ‘RX2 MIX1 INP1’,0

It could be that the audio and display might be unrelated but it would be of great help if you can confirm that i am heading in the right direction?

Best Regards.


#4

Had this exact same problem. There is one more part of the dtsi that you need to comment out.

Try commenting out the entire &mdss_dsi0 block in your dtsi. Like so:

//&mdss_dsi0 {
// status = “ok”;
//
// port {
// dsi_out: endpoint {
// remote-endpoint = <&adv_in>;
// };
// };
//};

Once this is done, you should only see one sound card when you run: arecord -l

The output should look something like this:

card 0: DB410c [DB410c], device 1: WCD-Capture msm8916_wcd_i2s_tx1-1 []
Subdevices: 1/1
Subdevice #0: subdevice #0