On Sun, Nov 29, 2020 at 6:53 PM Pali Rohár pali@kernel.org wrote:
Now when usbtty serial console is fixed in U-Boot enable it for Nokia RX-51 board by default.
CONFIG_CONSOLE_MUX is already used and U-Boot console is available for all in/out devices. Therefore there is no need to have separate commands 'run sercon', 'run usbcon' and 'run vgacon', so remove them.
As space for U-Boot is limited to 256kB, disable some other unused options so CONFIG_USB_TTY can be enabled.
Nokia RX-51 does not have easily accessible UART serial console so the only option for easy debugging is to use device's keyboard+screen or this usbtty serial console over USB.
I think it's not a good idea to revive usbtty. I was recently playing around f_serial.c (I can send you the half baked stuff, which by a lot of twisted code in DWC3 driver is not working properly, actually almost not working) and I think that would be the right thing to do.
usbtty quite old, intrusive way of serial console via USB supported only by outdated hardware (like this Nokia N-900), while f_serial gotta work on better recent base. And I believe musb should be, if needed, patched to support composite devices.
So, kinda disagreement from my side as a summary on this. But disclaimer, I'm not a maintainer here, just my 2 cents.