I found that latency of GPIO interrupt handlers is big and unstable.
On other ARM Cortex-A7 systems, for example i.MX6ULL, I used CONFIG_PREEMPT_RT enabled in kernel configuration to get interrupt latency stable in range 5-10 us.
Is it possible to use this option with Legato and WP76/77 modems? Any experience? Or other way to struggle with latency should be used?