On Tue, Apr 26, 2022 at 03:24:38PM +0300, Ilpo Järvinen wrote: > This patchset adds RS-485 support to the DW UART driver. The patchset > has two main parts. The first part adds HW support for RS-485 itself > in various modes of operation and the second part focuses on enabling > 9th bit addressing mode that can be used on a multipoint RS-485 > communications line. > > To configure multipoint addressing, ADDRB flag is added to termios > and two new IOCTLs are added into serial core. Lukas Wunner brought up > during v1 review that if this addressing is only going to be used with > RS-485, doing it within rs485_config would avoid having to add those > IOCTLs. There was some counterexample w/o further details mentioned for > RS-232 usage by Andy Shevchenko. I left the IOCTL approach there but if > somebody has further input on this, please voice it as it is user-space > facing API. > > I decided to rewrite the UART_CAP_NOTEMT patch from scratch myself > based on Uwe Kleine-König's earlier suggestion and include it to this > series. To make waiting for a single character easy and to avoid > storing it per purpose in the uart drivers, I decided to add > frame_time into uart_port. It turned out to beneficial also for serial > core which had to reverse calculate it from uart_port->timeout). I was > thinking of removing uart_port->timeout entirely and derive the value > timeout from frame_time and fifosize where needed but I was not sure > if that's ok to do lockingwise (not that fifosize is a variable that > is expected to change so maybe I'm just being too cautious). I've applied the first 4 now, thanks. greg k-h
