SPI device-tree question for Thor module

Robotics & Edge Computing Jetson Systems Jetson Thor
,
1

I’m currently creating the device-tree for our custom board and working with SPI. Looking in to the file `tegra264-p3834-0000.dtsi`there are some SPI-busses enabled there with `tegra-spidev`on CS0.

                spi@810c590000 {
                        status = "okay";
                        spi@0 {
                                /* chip select 0 */
                                compatible = "tegra-spidev";
                                reg = <0x0>;
                                spi-max-frequency = <50000000>;
                        };
                };

                spi@c6c0000 {
                        status = "okay";
                        spi@0 {
                                /* chip select 0 */
                                compatible = "tegra-spidev";
                                reg = <0x0>;
                                spi-max-frequency = <50000000>;
                        };
                };

                spi@810c440000 {
                        status = "okay";
                        spi@0 {
                                /* chip select 0 */
                                compatible = "tegra-spidev";
                                reg = <0x0>;
                                spi-max-frequency = <50000000>;
                        };
                };

                spi@810c450000 {
                        status = "okay";
                        spi@0 {
                                /* chip select 0 */
                                compatible = "tegra-spidev";
                                reg = <0x0>;
                                spi-max-frequency = <50000000>;
                        };
                };

Are those SPI-busses used on the compute module (P3834)?

3

Hi p.bergin,

You can refer to https://elinux.org/Jetson/L4T/peripheral/#Mapping for the SPI mapping.
Please also refer to the Chapter 13. SPI of Jetson Thor Series Modules Design Guide for the available SPI interfaces.

4

Thank you! Great additional info and I don’t need to try all of them next time to find the mapping. I suggest you copy that piece of information in to your “Nvidia Jetson Linux Developer Guide→Jetson Module Adaption and Bring-Up” guide.

But this doesn’t really answer my original question. The dts file tegra264-p3834-000.dtsi is from what I understand a way to describe the compute module P3834. In there you have defined the SPI busses and bound them to tegra-spidev. When I now want to use one SPI bus on my carrier board it will clash with the definition in the dts for P3834. Technically it is easy to just remove that node in my boards dts but I want to know the reason for them being specified in the dts for p3834? And to make sure they are not in use inside p3834. If they are not I recommend you removing them from P3834’s dts file and for dev-kit move them to the dst for p4071.

5

There’re many device tree files in the sources.
tegra264-p3834-000.dtsiis the device tree for the P3834 module.
I think all boards with this module having those SPI interfaces available so that we listed there. For the custom carrier board, we would suggest you creating the overlay board dtsi to contain the available device nodes according to your custom board design.