irq

I know I can use IRQ0, which is the system timer, but this is based on a 14.31818MHz clock, right? Is there anything offering greater precision? Thanks. Edit: Does anyone know what the Windows function QueryPerformanceCounter uses? "Precision" and "accuracy" mean different things. "The Earth's circumference is 40000.000000000 km" is precise, but not accurate. It's a bit more complicated with clocks: Resolution: time between ticks, or period of ticks. (You could probably call it "precision", but I think "resolution" has a more obvious meaning.) Skew: relative difference between nominal and

I am trying to retrieve the return address of an IRQ handler in my code. My aim is to save the value of the PC just before the watchdog timer expires and before the reset for debug purposes, using WDT_IRQHandler(). I am also testing this approach with other IRQs to check if I grasped the idea. But it seems I haven't. I have read the documentation available. I understood that when an exception happens, 8 registers are pushed to the stack: R0, R1, R2, R3, R12, LR, PC and XPSR. I have also read that the stack is automatically double word aligned. So in my mind, retrieving the return address is as

I have a driver code with handler function and thread function of request_threaded_irq similar to this: irq-handler fn() { /*disable device interrupt*/ i2c read from register; set disable bit to client-device-interrupt i2c write back; return IRQ_WAKe_THREAD; } irq-thread fn() { i2c read from register; .... .... /*enable device interrupt*/ i2c read from register; set enable bit to client-device-interrupt i2c write back; /*Rest of the operation*/ .......... .......... return IRQ_HANDLED; } I have few question with respect to above implentation. Will 2 i2c operation in "handler fn" takes

I posted this is the thread which discussed about request_threaded_irq but I did not get any reply. So I am posting it freshly. I am working on a touchscreen driver for capacitive touchscree. It used request_threaded_irq() call instead of request_irq(). I could not understand the basic difference betweeen two. It says :- Name request_threaded_irq — allocate an interrupt line Synopsis int request_threaded_irq (unsigned int irq, irq_handler_t handler,irq_handler_t thread_fn, unsigned long irqflags, const char *devname, void *dev_id); Arguments irq - Interrupt line to allocate handler - Function

I'm newbie on Linux Kernel. Currently, I looked into idle codes and had a quesition. When processor doesn't have any taks in their own runqueue then it may go into idle mode, specific WFI(wating for interrupt). (All I mentioned is about ARM architecture not X86. So something is wrong for X86.) After staying in WFI state, maybe other processor(not idle) want to spread their task to this, idle processor(by load balance). At that time a busy processor makes task imigrated. In my point of view, when the task is imigrated, the idle processor should wake up immidiatley to process the task. right?