• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 98 subscribers
  • Views 332 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

High interrupt latency

abraxas
Prodigy 230 points
Other Parts Discussed in Thread: OMAP3530

Hello,

i'm working on the OMAP3530 EVM with Angstrom, Kernel 2.6.29-rc3

In the attached file you can find my source-code.

1817.GPIO_ISR.zip

In short terms, it is a loadable module which does the setups for 2 GPIO ports( 1 input, 1 output) and the interrupt for GPIO-bank5

the input generates an interrupt. In the ISR, the output pin is set at the beginning and deleted before exit. Also there are some commands for the display sub-system, but you can ignore those

This works works just fine. The ISR itself takes around 1µs for exection (measured with oscilloscope).

But: The time between the interrupt source and the execution of the ISR is between 1ms and 800ms, which is obviously too high for any application.

I tried to move the interrupt to FIQ, but this didn't work out. The system freezes when the interrupt occurs.

Do you have any idea on how to speed this up?

  • 0
    Prodigy 230 points

    After 2 days of researching i could solve this:

    i had set detection on low-level AND falling edge.

    so, i guess i had a LOT of ISRs beeing executed and blocking each other.

    one change:

    register_write(adresse, 0x00000000); // enable irq assertion on low level detect

    and i got quite a steady latency of about 70µs