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: 1bcda09 ("serial: stm32: add support for RS485 hardware control mode") Cc: [email protected] Signed-off-by: Ilpo Järvinen <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Valentin Caron <[email protected]> Change-Id: I2f1f2c0675180f65c524948a9103d03abf8f4ee8 Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/linux-stm32/+/272029 Reviewed-by: CITOOLS <[email protected]> Reviewed-by: CIBUILD <[email protected]> Reviewed-by: Eric FOURMONT <[email protected]> Domain-Review: Amelie DELAUNAY <[email protected]>
STMicroelectronics · Oct 26, 2022 · 7f29f81 · 7f29f81
1 parent ef0c423
commit 7f29f81
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
@@ -110,6 +110,8 @@ static void stm32_usart_config_reg_rs485(u32 *cr1, u32 *cr3,  u32 baud,
 	*cr3 |= USART_CR3_DEM;
 	over8 = *cr1 & USART_CR1_OVER8;
 
+	*cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);
+
 	/* Assertion time */
 	tmp = stm32_usart_config_delay_rs485(cr1, delay_ADE, baud, over8,
 					     rs485_deat_dedt_max, rs485conf);