This is the backport of the RS485 polarity fixes discussed here: https://lkml.kernel.org/r/20221010085305.GA32599@wunner.de
It fixes RS485 DE initially set wrong on driver init, blocking other devices from transmitting on the bus.
Mizobuchi-san did the backport and tested on our imx-based platform, but we do not have any hardware to test other drivers.
The commits also apply cleanly on 5.15, and for 5.19 the second commit does (first one has already been picked up), but these have not been tested so would require more checking.
Kernels older than 5.10 do not have this particular polarity inversion problem and do not need this as far as I can see. (there might be other problems this addresses that I am not aware of though)
Thanks,
Lino Sanfilippo (1): serial: core: move RS485 configuration tasks from drivers into core
Lukas Wunner (1): serial: Deassert Transmit Enable on probe in driver-specific way
drivers/tty/serial/8250/8250_omap.c | 3 ++ drivers/tty/serial/8250/8250_pci.c | 9 +---- drivers/tty/serial/8250/8250_port.c | 12 +++--- drivers/tty/serial/fsl_lpuart.c | 7 ++-- drivers/tty/serial/imx.c | 8 +--- drivers/tty/serial/serial_core.c | 61 +++++++++++++++++++++++------ 6 files changed, 65 insertions(+), 35 deletions(-)