John has been actively participating in the upstream kernel community for over twenty years. He worked on kernel enablement on (usually large) x86 systems and improving the PREEMPT_RT kernel tree. He has also contributed a fair amount of code focusing on timekeeping, and is a co-maintainer in that area. John contributed to the Project ARA effort. Today he works on upstreaming the Android kernel patches and enabling AOSP devboards and form-factor devices with mainline. He is also the current maintainer for drm_hwcomposer.