I finally tracked down the patches that break the serial port on the BeagleBoard for kernels 5.8 or newer. I mentioned in another topic that the console output is slow. Once the root file system is mounted and welcome message is printed, no other output comes from the console. To get further output, you have to hold down or press any key for each line to be printed until you get to the login prompt. Logging in is slow and almost every command requires an extra press to get all of the output. Essentially, you have to cause serial port interrupts by pressing keys to get output. To get a working serial port for all kernels 5.8 to the latest, the following patches had to be reverted:
d2353bad2c1e ARM: omap2: fix omap5_realtime_timer_init definition
d86ad463d670 ARM: OMAP2+: Fix regression for using local timer on non-SMP SoCs
2ee04b88547a ARM: OMAP2+: Drop old timer code for dmtimer and 32k counter
e428e250fde6 ARM: dts: Configure system timers for omap3
036a3d42bb8f ARM: dts: Configure system timers for omap5 and dra7
Timer initialization was changed and the 32k counter was removed as the clockevent source? I am still learning the code. Apparently changing timer sources effected the serial port. I have not had time to dig further into fixing the issue. Lastly, the serial port driver for OMAP3 should be compiled into the kernel and not as a module. It makes boot time much faster. Rob, thanks for all your hard work. If there is some other place I should ask questions or post to, please let me know.