How to modify the clock frequency of SPI?

Robotics & Edge Computing Jetson Systems Jetson Orin Nano
1

Hello, teacher:
The core board I am using is Orin nano 4gb (JetPack5.1.5). Under the guidance of my teacher (KevinFFF), I completed the SPI loop test.
Now I need to communicate with SPI and MCU, but I don’t know how to change the SPI clock frequency of the core board. I want to change the SPI clock frequency to 1.5 MHZ. I hope the teacher can help me further. Thank you very much.

2

@KevinFFF

5

Hi 403199668,

Please share the full device tree and the result of the following commands on your board for further check.

$ cat /etc/nv_tegra_release
$ cat /etc/nv_boot_control.conf
6

图片
图片1883×423 21.2 KB

Please help me, teacher. If it’s particularly complex, just providing me with a general approach would be appreciated.

7

It would be great if you could provide me with some routines, similar to those for GPIO.

8

Please also provide the full device tree for further check.
There should be the related configuration in device tree.

9

Sorry. I didn’t reply to your message last week because I was on leave.
I am sending you the device tree now, and I hope you can continue to guide me.

dmesg.zip (129.9 KB)

10

You can update the spi-max-frequency property in SPI device node as following:

	spi@3210000 {
		iommus = <0x06 0x04>;
		#address-cells = <0x01>;
		dma-coherent;
		clock-names = "spi\0pll_p\0clk_m";
		nvidia,clk-parents = "pll_p\0clk_m";
		resets = <0x02 0x5b>;
		interrupts = <0x00 0x24 0x04>;
		clocks = <0x02 0x87 0x02 0x66 0x02 0x0e>;
		#size-cells = <0x00>;
		spi-max-frequency = <0x3dfd240>;
		..
		spi@1 {
-			spi-max-frequency = <0x2faf080>;
+			spi-max-frequency = <0x16e360>;
			compatible = "tegra-spidev";
		..

Or you can simply specify the SPI clock frequency from user space with -s option:

$ sudo spidev_test -D /dev/spidev0.0 -s 1500000