https://www.phoronix.com/scan.php?page=news_item&px=Linux-5.3-Dropping-FMC
"The FMC bus Linux code implements much of its own functionality right now that with a re-engineered subsystem could better re-use existing Linux kernel functionality around FPGA, GPIO, and I2C subsystems among other fresh design improvements. But at this time they don’t have an active maintainer/developer/organization stepping up to do a clean slate design of this subsystem. "