Hello, I just had the same issue this month. The keyboard and the trackpad both stopped working and the only was to fix it was to reboot. I also noticed in the log the message:
"Error: AppleHSSPIController::doSPITransfer NAK received from device" followed every time by
"Error: AppleHSSPIController::doSPITransfer CRC from device was invalid: compu..." and sometimes
"Error: AppleHSSPIController::InterruptOccurred Failed to transfer interrupt data with Err (0x00002eb)".
My MBP Early 2015 was still under warranty and the support told me it was related to a connector between the trackpad and the keyboard formally called "SVC,CABLE,IPD FLEX,HA COPPER,13" MBP" on the invoice. The Apple's Genius ran some diagnostic tests but he show me the results and everything was 100% fine, including the top case.
The repair costs 89€ in France (10€ for the cable itself, 79€ for the hardware fix). Hopefully the repair only takes up to 48 hours (or so they told me, it's been around 5 hours and I'm patiently waiting, I already brought my MBP for other issues and the repairs were fast).