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Questions tagged [device-tree]

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

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33 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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0answers
66 views

PPS GPIO with Buildroot image on Raspberry Pi 3

I'm a beginner with 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 ...
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17 views

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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1answer
28 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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41 views

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
43 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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0answers
21 views

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
109 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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26 views

Kernel driver, is pinctrl-0 property always needed with GPIO overlay?

I'm creating a kernel driver for SPI controlled display, which is meant to be working with Raspberry PI. I'm not sure about a one thing that I see sometimes in device tree overlays created by other ...
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3answers
110 views

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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0answers
115 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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0answers
39 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
221 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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0answers
114 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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0answers
24 views

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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0answers
100 views

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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0answers
120 views

embedded system no longer boots via eMMC - Initramfs unpacking failed: junk in compressed archive [closed]

I have Arch linux on multiple Embedded boards that are similar to Odroid C2. To resolve a DTB file issue, I wrote dtb.img to /dev/dtb of the eMMC via the command : dd if="/boot/dtb.img" of="/dev/dtb"...
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1answer
503 views

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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0answers
22 views

Device tree - defining peripherials switched off at boot

I have a board with i2c device(accelerometer) connected to mcu. I inserted the device node to my device tree file and everything works fine - device is detected, i can read measurements etc. However,...
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0answers
65 views

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
55 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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2answers
542 views

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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0answers
308 views

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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1answer
158 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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0answers
106 views

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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0answers
339 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 ...
2
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1answer
360 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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0answers
41 views

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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0answers
303 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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0answers
213 views

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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2answers
2k views

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 ...
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2answers
3k views

What are the values of the device tree interrupts property?

I'm trying to understand the device tree interrupts property and can not find a good explanation. For example if there is a node with the following lines: interrupt-parent = <&gpio5>; ...
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0answers
309 views

Change device name in /sys/class

I would like to know if there is a way to rename device under sysfs? For example, I have a class regulator with severals devices under it # ls /sys/class/regulator/ regulator.0 regulator.11 ...
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1answer
2k views

How to debug a driver failing to bind to a device on Linux?

I am trying to figure out why the following device is not setup to its driver on my Creator CI20. For reference I am using a Linux kernel v4.13.0 and doing the compilation locally: make ARCH=mips ...
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0answers
59 views

Jetson-K1 board slower than expected — “missing clock-frequency property”

I did some lmbench with my Jetson board with Tegra-K1 and Debian Stretch and got only 3900 for the STREAM copy (online I find 6430) and 2730 for the scale (online 6400). When just adding ...
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1answer
504 views

What is the difference between board level and Soc level information in DTS(device tree source) and DTSI?

For Device Tree Blob it says several boards can use one SoC so the SoC level information is included in board level in order not to be duplicated(DTSI is included in DTS). So 1.What is considered to ...
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1answer
282 views

Register r1 and r2 in boot process [closed]

Please tell me about the register r1 and r2 that bootloader uses to pass the information to the kernel. What are they? where are they located? and some details.
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1answer
525 views

What is the need of device tree in linux?

I know device tree used to map the actual hardware information with the device, but for the drivers can't we do it through the driver itself, if that is possible then what is the need of device tree. ...
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1answer
616 views

Confusion regarding #interrupt-cells configuration on PCA9555 expander

I'm trying to setup a device tree source file for the first time on my custom platform. On the board is a NXP PCA9555 gpio expander. I'm attempting to setup node for the device and am a bit confused. ...
3
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1answer
95 views

dtoverlay parameters being ignored

Attempting to calibrate a touchscreen, only the first of xmin, xmax, ymin, ymax is accepted. No matter what order, only the first has any effect. dtoverlay=ads7846,penirq=25,speed=10000,penirq_pull=2,...
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0answers
1k views

current question: How can I decompile an arm firmware file, to get the device tree file?

I am trying to flash libreelec on an android TV box without having an image I could throw in the libreelec toaster. On the RPi it was quite simple, here I guess I have to compile stuff, I don't really ...
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1answer
3k views

U-boot could not find a valid device tree

I have a problem: my device (an Atmel SAMA5D27 Xplained board) won't boot after my attempt to flash a new device tree. Here's what I did (details are at the end of this message): I downloaded the ...
3
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1answer
776 views

Is a device tree blob tied to a specific linux kernel version?

I was asking myself if a certain dtb that works with linux kernel version 3.18 is compatible with a linux kernel version 4.9. I suppose not, because kernel code concerning the device tree likely ...
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0answers
27 views

Is there information such as Operation Mode (Booting Mode) in the device tree?

Good morning. I am studying Device Tree of Kernel. I use an ARM board. According to the information of Operation Mode(Booting Mode) Register, the device medium used for booting the ARM board is set ...
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1answer
73 views

Why are ARM SoCs so seemingly hard to handle with the Kernel?

When I have some Linux distribution installed on a x64 system, for example I can pretty much unplug my storage drive put it into another x64 machine, install a few HL drivers, like the graphics driver ...
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0answers
88 views

Trying to understand device tree entry for usart

I'm pretty new to device tree programming, I'm trying to understand the interrupts line that shows up in the device tree for SAMA5D36 USART dts definition: usart2: serial@f8020000 { compatible = "...
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1answer
171 views

U-Boot : boot without reloading DTB

I'm using U-Boot on a Raspberry Pi Compute Module. The boot process is : RPi firmware --> U-Boot --> Linux I'm setting up some things about devices in the config.txt, that is used by the RPi firmware....
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0answers
166 views

Device Tree Overlay fragment notifies and loads children twice

I have the following device tree overlay fragment, and when it's loaded, spidev is added twice: fragment@0 { target = <&fpga>; __overlay__ { #address-cells = <1>; ...
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0answers
85 views

Device load on initramfs broke on dist-upgrade

I'm working on raspberry, with raspbian wheezy, for a fun embedded project. For this project, i need to display the project logo on the integrated touchscreen (tontec mz61561) as soon as it is powered....
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0answers
302 views

How do i Get SPI to work on allwinner A20 with kernel 4.4

I have configured the DTS file as required, am building my system using buildroot. find attached configuration file for buildroot and the configured DTS file. Up-to this point i can see the spidev ...