From 5c5f44e36217de5ead789ff25da71c31c2331c96 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Mon, 27 Jun 2022 18:07:52 +0300
Subject: [PATCH] serial: stm32: Clear prev values before setting RTS delays
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Git-commit: 5c5f44e36217de5ead789ff25da71c31c2331c96
Patch-mainline: v5.19-rc7
References: git-fixes
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 <stable@kernel.org>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220627150753.34510-1-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 b7b44f4050d4..0973b03eeeaa 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -72,6 +72,8 @@ 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
--
2.35.3