How to disable hdmi sound output in kernel

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Xavier
1

Hi everyone
i want to disable the output about the hdmi’s sound in kernel
so what should i do, i dont find the device tree or menuconfig about the hdmi output which i can set to disable the hdmi sound function.
The device is AGX Xavier
The version is <Linux dev-desktop 4.9.201-tegra #2 SMP PREEMPT Mon Apr 12 20:42:57 PDT 2021 aarch64 aarch64 aarch64 GNU/Linux>
The L4T is # R32 (release), REVISION: 5.1, GCID: 26202423, BOARD: t186ref, EABI: aarch64, DATE: Fri Feb 19 16:50:29 UTC 2021.

Thank you very much!

3

Hello,

Do you want to totally disable it from kernel or disabling it from the userspace configuration is also fine for you?

5

Hi waynewww
i want to choose the way which can disable the hdmi port send the singnal without sound data

6

Hi,

You can try to remove from the makefile of tegra display controller, so that it will not enable the audio.

kernel/nvidia/drivers/video/tegra/dc-> Makefile.
obj-$(CONFIG_TEGRA_HDA_DC) += hda_dc.o

7

Hi WayneWWW

Thank you for your reply.
I set change the Makefile and close the config option And now some .c file need it , i dont know which file i can close to make sure the hdmi can work well

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UPD kernel/config_data.h
CC kernel/configs.o
LD kernel/built-in.o
CC drivers/video/tegra/dc/dp.o
CC drivers/video/tegra/dc/hdmi2.0.o
LD drivers/video/tegra/dc/built-in.o
LD drivers/video/tegra/built-in.o
LD drivers/video/built-in.o
LD drivers/built-in.o
GEN .version
LD vmlinux.o
MODPOST vmlinux.o
CHK include/generated/compile.h
UPD include/generated/compile.h
CC init/version.o
LD init/built-in.o
drivers/built-in.o: In function tegra_hdmi_edid_eld_setup': /home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/nvidia/drivers/video/tegra/dc/hdmi2.0.c:570: undefined reference to tegra_hdmi_setup_hda_presence’
sound/built-in.o: In function hdmi_pcm_close': /home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/kernel-4.9/out/../sound/pci/hda/patch_hdmi.c:1876: undefined reference to tegra_hdmi_audio_null_sample_inject’
sound/built-in.o: In function generic_hdmi_playback_pcm_prepare': /home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/kernel-4.9/out/../sound/pci/hda/patch_hdmi.c:1815: undefined reference to tegra_hdmi_audio_null_sample_inject’
/home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/kernel-4.9/out/…/sound/pci/hda/patch_hdmi.c:1819: undefined reference to tegra_hdmi_setup_audio_freq_source' /home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/kernel-4.9/out/../sound/pci/hda/patch_hdmi.c:1812: undefined reference to tegra_hdmi_audio_null_sample_inject’
sound/built-in.o: In function hda_tegra_create_sysfs': /home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/nvidia/sound/pci/hda/hda_tegra.c:768: undefined reference to tegra_hda_get_switch_name’
/home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/kernel-4.9/Makefile:1102: recipe for target ‘vmlinux’ failed
make[1]: *** [vmlinux] Error 1
make[1]: Leaving directory ‘/home/zhou/lab/nvdia_sdk/sdk/JetPack_4.5.1_Linux_JETSON_AGX_XAVIER/Linux_for_Tegra/sources/kernel/kernel-4.9/out’
Makefile:171: recipe for target ‘sub-make’ failed
make: *** [sub-make] Error 2

8

Or you can try to comment out tegra_hda_init in tegra_dc_hdmi_init in hdmi2.0.c.

9

Hi

I comment out tegra_hda_init in tegra_dc_hdmi_init in hdmi2.0.c. But it still has sound singnal output. By the way the board use the hdmi1.4 interface

10

Please also disable tegra_hda_enable in hdmi2.0.c.

11

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image1440×1080 193 KB

i changed but still have

12

What is your method to update kernel?

13

make ARCH=arm64 O=$TEGRA_KERNEL_OUT Image -j8

./flash.sh -r -k kernel jetson-xavier mmcblk0p1

14

What is your jetpack version?

15

JetPack_4.5.1_Linux_JETSON_AGX_XAVIER

16

Please add arbitrary string in the hdmi2.0.c driver and re-build it again.

Directly copy and replace the old image in /boot/Image on your device. Reboot the device and see if your string shows up in dmesg.

The default path of kernel is the /boot/Image. The partition “kernel” will only be used when /boot/Image is missing or broken.

17

Hi

it’s ok now,thank you very much.
By the way, would you tell me what can i do to confirm the true version i flash to the board?

18

Do you mean where is the place to load kernel?

19

no, for EX. In the past i use the command “cat /proc/version” to confirm the firmware version, But now, for xavier it may be dont work very well

20

The jetpack version could be checked by /etc/nv_tegra_release.

21

OK, thanks very much

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