Could someone explain the relationship between dce and nvidia display driver?

I’m confused by the usage of the GPIO PM.00 for HDMI.
In Jetson-Linux r35.4.1 GA Release Notes, it says:

This change is needed because the GPIO_M_0 GPIO pin is used for the HDMI hotplug. In Orin,
the access to this pin should be limited only to the DCE firmware.

But we also need to change kernel dtb as below:

        display@13800000 {
+               os_gpio_hotplug_a = <&tegra_main_gpio TEGRA234_MAIN_GPIO(M, 0) GPIO_ACTIVE_HIGH>;
                status = "okay";
        };

My question is: which one is the real ‘owner’ of PM.00, and what is the relationship between dce and nvidia display driver?

Actually the kernel dtb will be copied to dce dtb during flash process.

Thus, the purpose of adding this to dtb is for this step. Not really for kernel.

1 Like

Hi WayneWWW,
Thanks for your reply.
So dce directly communicate with the hdmi monitor, and kernel communicate with dec through RPC?
And what is the kernel driver “tegra-dce”(.compatible = “nvidia,tegra234-dce”) for?

You can refer to kernel/nvidia/drivers/platform/tegra/dce/

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