v1: https://patch.msgid.link/20250923221756.26770-1-marnix.rijnart@iwell.eu Changes: * Added fixes tags * Cc stable

Commit 4afeced ("serial: core: fix sanitizing check for RTS settings") introduced a regression making it impossible to unset SER_RS485_RTS_ON_SEND from userspace if SER_RS485_RTS_AFTER_SEND is unsupported. Because these devices need RTS to be low on TX (fecf27a) they are effectively broken.

The hardware supports both RTS_ON_SEND and RTS_AFTER_SEND, so fix this by announcing support for SER_RS485_RTS_AFTER_SEND, similar to commit 068d35a.

Fixes: 4afeced55baa ("serial: core: fix sanitizing check for RTS settings") Fixes: fecf27a373f5 ("serial: 8250_pci: add RS485 for F81504/508/512") Cc: stable@vger.kernel.org Signed-off-by: Marnix Rijnart marnix.rijnart@iwell.eu --- drivers/tty/serial/8250/8250_pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index 152f914c599d..a9da222bd174 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -1645,7 +1645,7 @@ static int pci_fintek_rs485_config(struct uart_port *port, struct ktermios *term }

static const struct serial_rs485 pci_fintek_rs485_supported = { - .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND, + .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND, /* F81504/508/512 does not support RTS delay before or after send */ };