The request_irq() is suitable for handling simple and quick interrupt processing tasks and request_threaded_irq() is used for more complex interrupt handling that requires additional processing time and can tolerate the delay caused by executing in a separate thread.
These are two main functions for requesting to handle interrupts: request_irq and request_threaded_irq.
Below are the the difference between these,
request_irq():
- This function is standard interrupt handler used for requesting the interrupt handler.
- Here the interrupt handler is going to execute in interrupt context, it means, it doesn't create a separate kernel thread, it runs directly in the interrupt context.
- The reason, interrupt handler should be fast and should not block to avoid delaying the interrupt processing to impact system performance.
- Basically, request_irq is used when the interrupt handling can be processed quickly and doesn't require time-consuming operations or complex.
request_threaded_irq():
- This function is threaded interrupt handler used to request the handling of an interrupt.
- Here the handler is executed in a separate kernel thread context, which allows for time-consuming operations and more complex more complex to be performed.
- It is executed outside of the interrupt context, allowing it to perform blocking or longer-duration operations without affecting the interrupt latency.
- Basically, request_threaded_irq is used when the interrupt handling requires more processing time, for example accessing hardware registers, executing lengthy computations or performing I/O operations.