Config Jetson Nano Pin pcc4 as mcp2515 interrupt pin problem

Autonomous Machines Jetson & Embedded Systems Jetson Nano
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1

Hi!
I have connect mcp2515 module to jetson nano 4gb board, follow the guide: Unofficial Guide to using the MCP2515 can module on the Jetson Nano .
The mcp2515 works with the pin connect same as guide mention. When I change the interrupt pin from PZ0 to PCC4, the problem came out. I found the problem maybe is the Pin(PCC4) has already occupy by the extcon driver. I try to set the pcc4(pin228) by

    echo 228 > /sys/class/gpio/export.

And I got follow output:

Write error: Device or resource busy.

I look through file : cat /sys/kernal/debug/gpio find out gpio-228 seemd occupy by extcon:

gpio-228 (                    |extcon:extcon@1     ) in  hi IRQ

I want to change the extcon gpio pin. So I try to recompile the dtb file(tegra210-p3448-0000-p3449-0000-b00.dtb) and reconfig the
extcon@1 gpio setting as follow:

extcon@1 {
			compatible = "extcon-gpio-states";
			reg = <0x1>;
			extcon-gpio,name = "VBUS";
			extcon-gpio,cable-states = <0x0 0x1 0x1 0x0>;
			gpios = <0x5b **0xe5** 0x0>;
			extcon-gpio,out-cable-names = <0x1 0x2 0x0>;
			wakeup-source;
			#extcon-cells = <0x1>;
			nvidia,pmc-wakeup = <0x3c 0x0 0x36 0x0>;
			linux,phandle = <0x4d>;
			phandle = <0x4d>;
		};

Then, I copy the compiled refine dtb file to the /boot/ folder and reboot the nano. The problem still there.

cat /proc/interrupts
>   327:          0          0          0          0      GPIO 228 Edge      extcon:extcon@1

I want to know could I use pcc4(usb_vbus_en0_pcc4) pin as an interrupt of mcp2515 ? How to disable the extcon driver to release the pcc4 pin?
By the way, the usb_vbus_en0_pcc4 pin descript is generate by the spreadsheet of jetson nano as follow:

usb_vbus_en0_pcc4 {
				nvidia,pins = "usb_vbus_en0_pcc4";
				nvidia,function = "rsvd1";
				nvidia,pull = <0x0>;
				nvidia,tristate = <0x1>;
				nvidia,enable-input = <0x1>;
				nvidia,io-high-voltage = <0x0>;
			};

Thanks.
BR

3

hello qpeng05041,

you may modify device tree and also revise the driver side for not using this pin.

4

Hello JerryChang,
Thanks you for reply my question. I don’t familiar with the device tree and extcon driver.
I try to modify the device tree as follow, but none of the methods can release the pcc4 pin.

extcon@1 {
			compatible = "extcon-gpio-states";
			status = "disabled";			
			reg = <0x1>;
			extcon-gpio,name = "VBUS";
			extcon-gpio,cable-states = <0x0 0x1 0x1 0x0>;
			//gpios = <0x5b 0xe5 0x0>;              ------------------------------modify here ----------------------------
			extcon-gpio,out-cable-names = <0x1 0x2 0x0>;
			wakeup-source;
			#extcon-cells = <0x1>;
			nvidia,pmc-wakeup = <0x3c 0x0 0x36 0x0>;
			linux,phandle = <0x4d>;
			phandle = <0x4d>;
		};

chosen {
		nvidia,tegra-porg-sku;
		stdout-path = "/serial@70006000";
		nvidia,tegra-always-on-personality;
		no-tnid-sn;
		bootargs = "earlycon=uart8250,mmio32,0x70006000";
		nvidia,bootloader-vbus-enable = <0>;       ------------------------------modify here ----------------------------
		nvidia,fastboot_without_usb;
		nvidia,gpu-disable-power-saving;
		board-has-eeprom;
		firmware-blob-partition = "RP4";

		plugin-manager {
		};

		verified-boot {
			poweroff-on-red-state;
		};
	};

xudc@700d0000 {
		compatible = "nvidia,tegra210-xudc";
		reg = <0x0 0x700d0000 0x0 0x8000 0x0 0x700d8000 0x0 0x1000 0x0 0x700d9000 0x0 0x1000>;
		interrupts = <0x0 0x2c 0x4>;
		clocks = <0x26 0x121 0x26 0x9c 0x26 0x13e 0x26 0x122 0x26 0x11e>;
		nvidia,xusb-padctl = <0x49>;
		iommus = <0x30 0x15>;
		status = "okay";
		charger-detector = <0x9e>;
		hvdd_usb-supply = <0x4c>;
		avdd_pll_utmip-supply = <0x3b>;
		avddio_usb-supply = <0x44>;
		avddio_pll_uerefe-supply = <0x43>;
		//extcon-cables = <0x4d 0x1>;           ------------------------------modify here ----------------------------
		//extcon-cable-names = "vbus";         ------------------------------modify here ----------------------------
		phys = <0x4a>;
		phy-names = "usb2";
		#extcon-cells = <0x1>;
	};

xusb@70090000 {
		compatible = "nvidia,tegra210-xhci";
		reg = <0x0 0x70090000 0x0 0x8000 0x0 0x70098000 0x0 0x1000 0x0 0x70099000 0x0 0x1000>;
		interrupts = <0x0 0x27 0x4 0x0 0x28 0x4 0x0 0x31 0x4>;
		nvidia,xusb-padctl = <0x49>;
		clocks = <0x26 0x59 0x26 0x11d 0x26 0x9c 0x26 0x11f 0x26 0x122 0x26 0x11e 0x26 0xff 0x26 0xe9 0x26 0x107>;
		clock-names = "xusb_host", "xusb_falcon_src", "xusb_ss", "xusb_ss_src", "xusb_hs_src", "xusb_fs_src", "pll_u_480m", "clk_m", "pll_e";
		iommus = <0x30 0x14>;
		status = "okay";
		hvdd_usb-supply = <0x4c>;
		avdd_pll_utmip-supply = <0x3b>;
		vddio_hsic-supply = <0x42>;
		avddio_usb-supply = <0x44>;
		dvdd_sata-supply = <0x45>;
		avddio_pll_uerefe-supply = <0x43>;
		//extcon-cables = <0x4c 0x1>;              ------------------------------modify here ----------------------------
		//extcon-cable-names = "id";                ------------------------------modify here ----------------------------
		phys = <0x4a 0x4e 0x4f 0x50>;
		phy-names = "usb2-0", "usb2-1", "usb2-2", "usb3-0";
		//#extcon-cells = <0x1>;
		nvidia,pmc-wakeup = <0x3c 0x1 0x27 0x4 0x3c 0x1 0x28 0x4 0x3c 0x1 0x29 0x4 0x3c 0x1 0x2a 0x4 0x3c 0x1 0x2c 0x4>;
		nvidia,boost_cpu_freq = <0x4b0>;
	};

I wonder that if I just modify the vbus to another pin, or disable the extcon function in the device tree only, pin pcc4 or gpio 228 will not be occupied by extcon: extcon@1. Is the extcon driver must be revise? Is the device tree determind the extcon@1 interrupt pin(gpio228)?

327:          0          0          0          0      GPIO 228 Edge      extcon:extcon@1

Thanks

6

Since you said you are not familiar with device tree, then I wonder what is your method to update device tree after you changed it?

7

I recompile the dtb file(tegra210-p3448-0000-p3449-0000-b00.dtb) to get .dts file, using following command:

 dtc -I dtb -O dts -o my-overlay.dts /boot/tegra210-p3448-0000-p3449-0000-b00.dtb

After reconfig the dts file, I use flollowing command:

dtc -O dtb -o tegra210-p3448-0000-p3449-0000-b00.dtbo -@ my-overlay.dts
sudo cp tegra210-p3448-0000-p3449-0000-b00.dtbo /boot
sudo reboot
8

By default, the dtb file is not read from rootfs. Which means what you are doing does not update the dtb.

You can either update it from host (re-flash is required) or add FDT field to your /boot/extlinux/extlinux.conf.

9

Hi WayneWWW,
I am extremely grateful for your help!!!
After I change the extcon@1 property in file (kernel_tegra210-p3448-0000-p3449-0000-b00-user-custom.dtb), It works.
Later, I will try to use another methods you have mentioned. Thanks again!!!

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11

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