TTymidi on latest raspberry kernel uses mostly
dtoverlay=midi_uart0
This Overlay should allow the user to set MIDI BAUD to 312500 on the uart, which the sys kernel don't let you change.
It should have been fixed. It isn't.
recent bento-ttymidi uses sys/termios, ioctls, and POSIX to try change baud rate on TX and XR pins, uart.
ttymidi-sysex similarly, suffer from the same issue.
syslogs and dmesg shows the same error.
ttymidi tries to change the baud rate. This function is deprecated.
How can this be fixed?
Every single Midi hat made for the Pi, that uses standard Octocoupler design and not complex SPI-ARM workarounds,
are bound to not work. Every one is screwed. The creators. The users. Everyone.
And at raspberry foundations, no-one seems to care.