reset SMC to fix internal SD card reader

After upgrading my 2012 MacBook Air from 10.14.6 (Mojave) to 10.15.7 (Catalina) I began to experience weird problems (the fan running at full power; the secd application running all the time; stuttering video playback) culminating with the loss of my internal SD card reader. The reader no longer showed up in system profiler/system information. Using information from a 2021 community answer, I reset the SMC (system management controller) by holding shift-ctl-opt-power from a cold start, which returned the internal card reader to the system information report. I am leaving this breadcrumb for those who find the earlier suggestion to reset the SMC, but don't find a reply that it was successful.