On Thu, Aug 04, 2022 at 02:38:23PM +0000, Roosen Henri wrote: > unfortunately this commit, which has been backported to v5.4.x, seems > to break RS485 functionality on our iMX boards. What exactly broke? Are you seeing incorrect polarity after opening the tty but correct polarity after the first send? Or is polarity always incorrect? There have been reports about incorrect polarity after open and before the first send as a result of that committ, but they only concern a subset of drivers using the "em485" software emulation in 8250_port.c: https://lore.kernel.org/linux-serial/20220329085050.311408-1-matthias.schiffer@xxxxxxxxxxxxxxx/ imx.c does not use the em485 software emulation but rather a dedicated GPIO, and the way you've set it up looks correct to me. Some transceivers have both a DE and a !DE pin. Is the GPIO connected to the former? Thanks, Lukas
