From 0c8649a4978856240cfa46703f0179fd2a288419 Mon Sep 17 00:00:00 2001 From: Ilpo Järvinen Date: Mon, 27 Jun 2022 18:07:52 +0300 Subject: serial: stm32: Clear prev values before setting RTS delays MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 5c5f44e36217de5ead789ff25da71c31c2331c96 upstream. The code lacks clearing of previous DEAT/DEDT values. Thus, changing values on the fly results in garbage delays tending towards the maximum value as more and more bits are ORed together. (Leaving RS485 mode would have cleared the old values though). Fixes: 1bcda09d2910 ("serial: stm32: add support for RS485 hardware control mode") Cc: stable Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220627150753.34510-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/stm32-usart.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index d5a084ffde89..5e0b9f783cac 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -73,6 +73,8 @@ static void stm32_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE, *cr3 |= USART_CR3_DEM; over8 = *cr1 & USART_CR1_OVER8; + *cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK); + if (over8) rs485_deat_dedt = delay_ADE * baud * 8; else -- cgit v1.2.3