Questions tagged [device-tree]

A data structure for describing hardware. passed in boot time to kernel

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When is the devicetree parsed to populate the device list on arm64 architecture?

This question comes from my attempts to understand how a built-in platform device driver is initialized at boot time. I am using an embedded linux distro (Yocto) on a SoC (ARM + FPGA). The device ...
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How to add small changes to the Device Tree?

I made my own interface board for the Compute Module 4, but I noticed some peripherals are not enabled by default. Cameras and Displays are disabled as well as the USB. If I understand it correctly, I ...
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gpio_name_to_desc in gpiolib.c in Linux kernel should be externalized?

We have an embedded project, and for our purposes, it seems handy to name all the gpios in the gpio controller device tree stanza using gpio-line-names feature in device tree, mentioned in ...
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14 views

dtoverlay in x86 fedora

I'm messing around with a small x86 module (think raspberry pi, except not an ARM), running Fedora, and has the same concept of pluggable hardware "hats." I am trying to figure out if it's ...
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25 views

Unable to enable TLV320AIC3104 codec driver /simple sound card for iMx8M with SAI2 BCLK/MCLK provided with external clock

I am trying to access codec driver (TLV320AIC3104) connected to iMX8M over I2C3 and SAI2 lines. The codec clocks bclk is 4096000 and it is provided from an FPGA and its mclk is grounded. iMx8M SOM ...
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Linux 4.19: apply devicetree overlay on live system

Is it possible to apply a devictree overlay on a live system? We have an embedded system that has some optional hardware. We would like to load the devicetree information after Linux booted. Reqaon ...
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BeagleBone Black UART 1 config

Recently I compiled my own linux system using kernel 5.10.23, and I made modifications to the device tree in order to activate UART 1 PIN (9-24) and (9-26). I have /dev/ttyS1 available for R/W ...
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35 views

How to disable TX path of ethernet PHY in embedded linux?

In a yocto-based embedded device I use ethernet only to receive UDP packets. Now I want save energy as the device (as well as the UDP transmitter) is battery powered, and the ethernet PHY (a micrel ...
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14 views

Modified kernel module doesn't load on boot- is the old one being cached somewhere

I'm modifying the qca7000 kernel module slightly by adding some debug messages (qcaspi.ko). I compile, run depmod then reboot. However my debug messages do not show up on dmesg. If I rmmod qcaspi then ...
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Network use USART

Hy I wanted to implement a Network driver that uses the USART. So first I changed the Device-Tree to acces the USART. Then I started to create my Network driver. In the init() method of the driver I ...
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Read i.MX7D nvmem via NVMEM_IMX_OCOTP: require extra Device Tree entries?

When using NVMEM_IMX_OCOTP to configure a Buildroot Device Tree (and hence 'imx-ocoto.c'), and to read the i.MX7D nvmem to get the MAC address, is it actually necessary to add properties/nodes as ...
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Platform driver's probe function isn't called

I am developing a simple platform driver for beaglebone (but currently running on my virtual machine running Ubuntu) that uses device tree, but it doesn't seem like the probe function is being called. ...
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1answer
122 views

Linux, how to add "missing" i2c interface?

I'm working on an embedded project utilizing a Digi ConnectCore 6UL SBC Pro, and I know that dmesg should show me the three I2C interfaces after boot up like: i2c i2c-0: IMX I2C adapter registered i2c ...
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Definition and usage of Kernel/Linux DTS file with more than one MIPI DSI Display panel

I actually need some help of defining the kernel/linux DTS file and use it together with the uboot videoargs. In use is the 5.4.47 uboot and kernel/linux from a NXP imx8m YOCTO project. In uboot I ...
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1answer
5k views

fprintd: The driver encountered a protocol error with the device

I am trying to make work my finger print sensor thinkpad x390 yoga. I installed printfd package using yay. When I try to run fprintd-enroll, I get this error: Using device /net/reactivated/Fprint/...
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1answer
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Raspberry Pi 4B - Is Device tree binary dependent on kernel version?

I am trying to get my own custom Linux on a Raspberry Pi 4B. My status is this: I built the Linux 5.9.1 version, and have my own version of U-Boot, RFS with which I am able to successfully load and ...
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1answer
38 views

nvmem device tree naming pattern

In the nvmem.yml there is properties: $nodename: pattern: "^(eeprom|efuse|nvram)(@.*|-[0-9a-f])*$" I have a hard time finding the pattern in the source code itself. Where can I find ...
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1answer
304 views

Where is the device tree on the Linux machine, for e.g., Debian or Ubuntu?

These days we have device tree. I am wondering where can I see the device tree in my PC - i.e. Debian - Release: 9.11. When I look at the kernel config, I don't see the device tree. How come device ...
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1answer
314 views

Read MAC using Buildroot 20.20 NVMEM_IMX_OCOTP on i.MX7s

We are migrating from Buildroot 2018.02.9 (linux-4.14.85) to Buildroot 2020.02.2 (linux-5.4.40), and have found that we can no longer read the MAC address on an I.MX7s SoC. The following indicates why:...
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126 views

Create and remove devicetree nodes at runtime for debugging

I am writing a simple Linux module on an embedded platform. For testing, I can load and unload it with modprobe etc., and my module_init code gets called. However, if I want to use the modern ...
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Specify minimum backlight level with pwm-backlight

I have a device that uses PWM for backlight. It is using the pwm-backlight driver. However, you can turn the backlight down so far that the screen turns off, and then it is hard to turn it on again ...
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314 views

Memory node of device tree in /proc doesn't match dtb

I'm trying to modify the memory node in a device tree for a zynqmp zcu102 board. However, something seems to be overriding this node somehow. I'm booting using a FIT image and u-boot. I've confirmed ...
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210 views

Getting configuration from dts file on x86 system

There is a requirement in a project where we have to take certain configuration values of a device from device tree. I was able to generate device tree blob (.dtb) from .dts file. There is apparently ...
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142 views

How to Load Device Tree From Separate File in U-Boot Image

I'd like to load the device tree from a separate dtb file. So in the end I'd like to end up with the following files on my boot partition: BOOT.BIN (first stage boot loader) image.ub (U-Boot second ...
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1answer
165 views

DeviceTree Overlay fails

Following setup here: TinkerBoard-S with rk3288 Chip running armbian with legacy Kernel 4.4.199 Now I would like to add an overlay to the existing one. Here is how the existing one looks like: ...
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455 views

Adding a DeviceTree Overlay for DSI for a RK3288

I'm trying to add a DSI configuration to my linux kernel. Actually i am using the following setup: Tinkerboard S (RK3288 Chip) Armbian with legacy Kernel 4.4.199 I have already found existing device ...
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1answer
1k views

Override mtdparts configured in kernel device tree

I've installed Debian Buster on a "ReadyNAS 102" via u-boot / serial console. I was following this tutorial. But, replaced used different links to download current the Debian installer and Device Tree ...
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1answer
384 views

WS2812 Device Driver in Linux Kernel

I was searching for a device driver to drive ws2812b addressable LEDs in the linux kernel but could not find any. Is there a specific reason that there are no drivers for these LEDs?
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Full duplex PCM bridge

I'm working on an embedded device, that runs Linux 4.14.79, that has 2 hardware PCM, one connected to a bluetooth chip and one to a GSM phone. My goal is to bridge those streams (bt-in -> gsm-out ...
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1answer
70 views

How does kbuild compare to the device tree?

I know KConfig serves to tune the C preprocessor, at the start of the Linux kernel compilation. And that the device tree is used to give a compiled kernel a description about hardware at runtime. How ...
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62 views

how does a gpiochipNN is selected or set in gpiolib kernel?

I am looking into kernel gpiolib and gpio-xilinx.c. I see that my device has only cat /sys/kernel/debug/gpio gpiochip0: GPIOs 960-1023, I am confused on how this 960 has arrived. How does the kernel ...
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1answer
952 views

RS485 hardware RTS on SC16IS752 not working when it is enabled in device tree overlay

I'm trying to make SC16IS752 (SPI to UART converter) work in RS485 mode by using device tree overlay (without running C application at boot). I took original overlay source for SC16IS752 from ...
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617 views

Device tree and passing parameter to serial driver from specyfic device overlay

I would like to pass linux,rs485-enabled-at-boot-time; flag/parameter to serial port driver configuration for sc16is752 device defined by this device tree overlay (unmodified file from Raspbian): /...
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1answer
1k views

Jetson TX2 device tree, i2c nodes and camera driver loading

I am a bit confused with behavior of Jetson TX2 when loading drivers for camera. Here is definition of IMX274 in device tree: i2c@3180000 { reg = <0x0 0x3180000 0x0 0x100>; ...
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1answer
587 views

How to debug an SDIO configuration problem?

We are trying to get an SDIO-based 802.11 module to work on an SDIO port of the beaglebone. We adapted the device-tree overlay provided by manufacturer to our hardware, compiled the driver, the driver ...
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149 views

How to fix MPU9250 configuration issue in device tree?

I have set up an i2c protocol which detects the mpu9250 at address 0x68. Now I want to configure the mpu and I have updated my dts file with the following lines of code: mpu9250@68 { compatible = ...
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1answer
685 views

Is there a way to delete an alias from an included dtsi file in a dts file?

The file at91sam9x5.dtsi in arch/arm/boot/dts has aliases that are undefined references after deleting nodes that are unneeded using /delete-node/. Unfortunately if I try to delete the aliases that ...
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1answer
975 views

Run script after module is loaded due to device tree

Why do I want this? I use the pwm-ir-tx kernel module to blast IR signals from my embedded device. However, when the pwm kernel module is loaded during the boot process, the pin is on high. It takes ...
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1answer
169 views

How to read back a fan speed?

I am on a custom board using an i.MX6. I am using Yocto (Pyro) to build my kernel (4.14.16). I am using the generic imx6qdl.dtsi device tree entry for PWM2 to drive the fan and it appears to work ...
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1answer
809 views

PPS GPIO with Buildroot image on Raspberry Pi 3

I using Buildroot trying to build a Linux image for the Raspberry Pi 3 in which I have access to pulse-per-second (PPS) inputs on one of the GPIO pins. First off, I have tried this with the standard ...
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1answer
908 views

How do I configure the Beaglebone Black PWM correctly

I have tried to get PWM working and am not having any success. I am using the TI Processor SDK with a modified version of the am335x-boneblack.dts device tree (see below) The PWM driver (ehrpwm1) ...
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2answers
194 views

How does the same Linux version work on different hardware

My understanding is that the kernel understands how to communicate with the different hardware in a system via specific device trees. How is it that I can download one version of Ubuntu and I am ...
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Can I generate a single device tree dts file from all the files in my device kernel?

I need to fix a driver that is using a node in the device tree, the problem is that the node and it's aliases are all over the place, separated through few different files with few overrides and it is ...
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1answer
4k views

mmc0 warning on SD card bootup of linux

I get the following warning on debian linux (kernel 4.18.8) bootup of my microchip sama5d3 board: mmc0: unrecognised SCR structure version 4 mmc0: error -22 whilst initialising SD card after spewing ...
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3answers
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How does Linux find/configure something like 'wlan0' when it is not a device that appears in /dev?

(On raspberry pi zero w, kernel 4.14y) It seems the wireless adapter chip isn't a device in the /dev fs, but is the name of something that 'ifconfig' knows about. I understand that this is an ...
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295 views

Device-tree blob (DTB) in a separate partition

Currently, I have the device-tree blob (DTB) appended to the Linux kernel. I would like to split the DTB from the kernel to an unique partition containing only the DTB similar to the figure 3 of the ...
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54 views

DT bindings for ADT7516 sensor

I have a BeagleBone green and ADT7516's evaluation board connected with SDA and SCL pins. When I do i2cdetect -y -r 2, I can see the i2c address as 0x4b and I am able to probe the adt7316 driver ...
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1answer
2k views

Linux Device Drivers - Probe function not called, but driver getting deferred

I've been trying to get an MCP2515 can controller working on a spi-gpio bus in my device tree, but the MCP251x driver's probe function never seems to actually be called. Oddly enough though, some ...
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452 views

Change device tree on boot

There is a hardware SPI device on my platform, but it doesn't appear in /dev. I read in internet that the hardware description is read during boor from device tree files (dtb). The problem is that I ...
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Devicetree parallel CSI OV7670

I'm currently trying to get an image with fswebcam out of my OV7670 camera, but I only get a completly green image. Could you look over my devicetree if I made some obvious mistakes? board-file.dts: ...