I have an issue installing an interrupt handler in a hardware driver, in this specific case for the am3358 e-capture unit eCAP0 on a Beaglebone Green.
I am running a build per , built with a Mainline 4.9.30-bone4 (non real time) kernel and the debian-8.7-minimal-armhf-2017-01-14 file system. The driver was developed and worked on an earlier 3.8 kernel, but now fails to receive any interrupts under the 4.9 kernel. The interrupt is registered with a call to: 31 is the interrupt number for eCAP0INT per table 6.3 in the am335x-techref. The call succeeds with a zero status, but the interrupt routine is never called even though events are detected by the eCAP unit. Furthermore, looking at the /proc/interrupts I see: Which shows that (1) no interrupts have been detected on IRQ 31, and (2) the third column lists a suspicious “44e07000.gpio” instead of INTC as most other interrupt lines do. The latter leads me to believe that the interrupt is not mapped appropriately from the capture unit, but rather to some sort of gpio mapping, although I do not know what the third and the fourth column in /proc/interrupts show. An attempt to probe for the interrupt using this code also fails with no detected interrupts: It sure looks to me that there is some sort of interrupt mapping/enabling that is new with the 4.x kernels which I am missing. Any help and explanation would be greatly appreciated!