This is a note to let you know that I've just added the patch titled
serial: stm32: Clear prev values before setting RTS delays
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-stm32-clear-prev-values-before-setting-rts-delays.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5c5f44e36217de5ead789ff25da71c31c2331c96 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Date: Mon, 27 Jun 2022 18:07:52 +0300
Subject: serial: stm32: Clear prev values before setting RTS delays
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From: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
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 <stable@xxxxxxxxxx>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220627150753.34510-1-ilpo.jarvinen@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/stm32-usart.c | 2 ++
1 file changed, 2 insertions(+)
--- 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 *
*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
Patches currently in stable-queue which might be from ilpo.jarvinen@xxxxxxxxxxxxxxx are
queue-5.4/serial-pl011-upstat_autorts-requires-.throttle-unthrottle.patch
queue-5.4/serial-stm32-clear-prev-values-before-setting-rts-delays.patch
