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serial: stm32: Clear prev values before setting RTS delays 

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: 1bcda09d29 ("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>
This commit is contained in:
Ilpo Järvinen 2022-06-27 18:07:52 +03:00 committed by Greg Kroah-Hartman
parent ec5ad33168
commit 5c5f44e362
1 changed files with 2 additions and 0 deletions
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2
drivers/tty/serial/stm32-usart.c
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@ -72,6 +72,8 @@ static void stm32_usart_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE,
*cr3 |= USART_CR3_DEM; *cr3 |= USART_CR3_DEM;
over8 = *cr1 & USART_CR1_OVER8; over8 = *cr1 & USART_CR1_OVER8;
*cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
if (over8) if (over8)
rs485_deat_dedt = delay_ADE * baud * 8; rs485_deat_dedt = delay_ADE * baud * 8;
else else