i.MX Processorsのトピックwhen external interruption is coming,sometime spend long time enter gic_handle_irq

when external interruption is coming,sometime spend long time enter gic_handle_irq

sofia_0571 — Thu, 23 Sep 2021 06:33:03 GMT

hi.

now make a test to know how long it take enter gic_handle_irq when extern interruption is coming.

GPIO5_3(is configured interrupt gpio) is connected to ADC_RDY(32Khz frequency output)

in-gpio147 and out-gpio146 is controled in gic_handle_irq.see the following:

static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)

{

gpio_set_value(147, atomic_read(&intr_probe)%2);//interrupt is coming,gpio147 output level is flipped

do {

...

} while (irqnr != ICC_IAR1_EL1_SPURIOUS);
gpio_set_value(146, atomic_read(&intr_probe)%2);///

}

discovery sometimes lost data, later found, when the interrupt comes to enter gic_handle_irq too late.below is grasping the underlying data waveform.how to optimize.thanks.

787835294_0-1632376706723.png

787835294_1-1632377617435.png

Re: when external interruption is coming,sometime spend long time enter gic_handle_irq

igorpadykov — Thu, 23 Sep 2021 10:17:54 GMT

Hi David

standard linux can not guarantee fixed interrupt latencies, in general one can try to analyze

it placing gpio toggling in code and observing it with oscilloscope, For low latency linux one can consider

Real-Time Edge Software

https://www.nxp.com/design/software/development-software/real-time-edge-software:REALTIME-EDGE-SOFTWARE

Best regards
igor

Re: when external interruption is coming,sometime spend long time enter gic_handle_irq

sofia_0571 — Mon, 27 Sep 2021 02:27:35 GMT

Planning to move this feature to the M4 core,The M4 interrupt is specified by the GIC?Will the interruption of the M4 be disturbed by the A53?