Questions tagged [device-tree]

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

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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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DSI-Panel (panel-simple-dsi) fails to get initialized

I am trying to get a DSI-Panel up and running. For this i am using armbian as a base system. I have built the distribution first with startard settings which has worked for an raspberry-pi display. ...
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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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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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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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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
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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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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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Modifying UARTCLK

Intro I am using an A20 SoC running Armbian and I try to run serial communication on a baudrate that can't be hit on standard configuration. What happens Configuring a serial interface (UART6 in my ...
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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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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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Is it possible to use User Mode Linux with a Device Tree?

When compiling linux kernel 4.2.0 for User Mode Linux architecture ($ARCH = um), I've checked the option 'Device Drivers->Device Tree and Open Firmware Support', but I couldn't find any documentation ...
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485 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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eCSPI with different MOSI, MISO and SCK per spi_device

The manufacturer's device tree setup for ecspi1: &ecspi1 { fsl,spi-num-chipselects = <1>; cs-gpios = <&gpio2 30 0>; pinctrl-names = "default"; pinctrl-0 = <&...
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Controlling pinmux from the command line

There are plenty of tutorials about configuring pin muxes in the device tree using the pin-ctl mechanism. However, is there a way to make these changes from the command line? /sys/kernel/debug/...
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How to connect USB keyboard to BeagleBone Black in my own kernel and root file system?

I built uboot, linux kernel and root filesystem for beaglebone black. I have logitech k120 for business usb keyboard. In menuconfig of kernel i selected logitech keyboard driver, usb driver, usb ...
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1answer
154 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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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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How to create directory in RAM at specified RAM address

It is about linux embedded (none hdd, uboot loads sw image from flash to RAM which is 2Gb). How to reserve 16Mb memory in RAM for directory let's call it "/pram? I want functionality - if someone ...
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190 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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325 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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69 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
304 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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Is it possible to use a phandle of an alias in a device tree overlay?

I have an alias with a phandle I want to use in a cell in an overlay: ublox1:/proc/device-tree/aliases# cat gpio0 | tr '\0' '\n' /ahb/apb/pinctrl@fffff400/gpio@fffff400 If you follow this path, it ...
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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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How do I rearrange the clock tree to get the clock I need?

I am using a LVDS display on an i.MX6 DualLite. The panel is supposed to be running at a clock of 51.2MHz. I am in the process of updating to a newer Yocto (Pyro) built BSP running 4.14.16. The ...
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2answers
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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
2k 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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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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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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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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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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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: ...
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How to initialize multiple I2C sound devices with one device tree overlay?

I am currently stuck in implementing a new device tree overlay to initialize two sound controller: PCM5142 and WM8804. The used board is the DACBerry ONE (https://www.osaelectronics.com/product/...
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How does kernel know which device tree to load?

Device tree is used at runtime on ARM devices to identify and load correct drivers with its configuration. But when I look into loaded DT at /proc/device-tree on my phone for example, there are many ...
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Is it possible to declare a regulator in the device tree that can power down the system

If I have, for example, a fixed-regulator declared in my device tree, how can I request Linux to call the disable function after shutting down? Note, I use a custom regulator driver (not fixed-...
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1answer
80 views

How can I tell my kernel not to place external drives before internal ones?

I have some internal drivers, which typically take the names /dev/sda ... /dev/sdc. However, if I plug in an external HDD and reboot, this gets reordered, with the external drive taking up /dev/sdb ...
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Uboot Hangs when Initrd size increased in FIT image

Im booting Linux on arm64 using FIT multi image (image + initrd + DTB). So if I increase the initrd size (from 16 MB -> 20MB) board hangs at "starting kernel"). However if I change the load address of ...
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BeagleBoneBlack device tree changes to add i2c device driver ()

I'm trying to run an i2c device driver on the BeagleBoneBlack using i2c2 pins [P9]: (19) I2C2_SCL, (20) I2C2_SDA. I can use i2c2 successfully from user space to control the same atmel touchscreen ...
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329 views

Want pulldown on gpio pin

I would like to have the default for certain input pins be a weak pulldown. I am using a sama5d36 running Debian 4.12.8. I modified the dts file as follows: ahb { abp { pinctrl@fffff200 ...
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What is the preferred way to unhog a hogged GPIO pin?

So I'm doing development on an ARM embedded system which is using the device trees. We're going to integrate a small PCB with a processor and support components onto a bigger PCB, which will be the ...
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494 views

Accessing I2C slave devices that are specified in Device Tree

I'm trying to communicate with a device over I2C from my BeagleBone Black, and I'm a bit curious as to the device tree's interpretation of I2C. I see that there are a couple of device nodes within ...
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1answer
567 views

Generate bootable ELF from bootloader, kernel, device tree, ramdisk

I'm new to Linux Kernel programming, and am pretty stuck with (what I think is) the last step in building my bootable image. For some background, we are trying to upload a complete OS image onto the ...
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Can you toggle a regulator device from the terminal?

I've been working on a custom embedded board, and set up a few pins as regulator-fixed in a custom device tree - they control power to devices on the board and some drivers need them provided as ...
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444 views

Loading a kernel module at run time using “compatible” property of device node in device-tree

If I know the "compatible" property string of a device(from the device tree), can I use it at runtime to load the corresponding kernel driver module? I do not have access to the driver source. I am ...
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Write to M25P80 Flash

I am looking for a way to move data onto a Micron M25P80 Flash Card over SPI bus on a Xilinx Zynq 7100 emulated in QEMU. I am not sure which driver to use. I would like to use the Cadence SPI driver ...
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Why do embedded systems need device tree while pcs don't?

When booting a kernel in an embedded device, you need to supply a device tree to the Linux kernel, while booting a kernel on a regular x86 pc doesn't require a device tree -- why? As I understand, on ...