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Tag: driver

Why open() has no ‘fd’ return in linux 1.0?

Since there is no return of ‘fd’, how does it read/write later for? ex: Answer open returns a value in there. The cast-to-void is used to signal the compiler that the return value is being deliberately ignored. The init function is the one where the current thread is prepared to execute the init program in user-space. init will expect the

Linux loading i2c drivers

I have linux 4.4 on my board. I also have two i2c devices with their driver. When I connect first device to board – i see in dmesg that _probe function called. When I don’t connect any device to board – in dmesg i don’t see _probe function. When I connect second device – in dmesg i don’t see _probe

Writing to Linux device driver causes infinite loop

I have been writing a kernel space device driver that can be read from and written to from user space. The open, read, release operations all work perfectly. The problem I am having is with the user-space code that should access the device driver and and write something to it. The user-space program writes to two files: 1) to a

Custom char device linux module under stock major (like “tty”)

I’m writing my first linux kernel module. It is a standard char device to communicate over a GPIO pin. It works like a charme. It is registered with its device name under /dev and in my own class name under /sys (it has some attributes available for configuration by the host application). My wish is to move my device under

Embedded Qt Mouse Pointer Not Showing Up

I’ve got a bit of an interesting problem here. There are plenty of threads I’ve found where people are working to hide or get rid of a cursor on an embedded Qt GUI…but I’m trying to get a cursor to show up on an embedded Qt GUI. I inherited a project that was ‘finished’ some time ago, and the person

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