From: Ilpo Järvinen Date: Mon, 27 Jun 2022 15:07:52 +0000 (+0300) Subject: serial: stm32: Clear prev values before setting RTS delays X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=8ef116a2a7383a390be42fd8554dc1680cc0ea77;p=linux.git serial: stm32: Clear prev values before setting RTS delays 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 --- diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 10e9f983de621..fc166cc2c856d 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -71,6 +71,8 @@ static void stm32_usart_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