From 8ab9e8ffdf0977ce5101a4d71b75655667eced5e Mon Sep 17 00:00:00 2001 From: Patrice Chotard Date: Wed, 31 May 2023 08:01:31 +0200 Subject: [PATCH] serial: stm32: BRR must be set only when usart is disable To avoid spurious chars, BRR register must only be written when USART is disabled. Signed-off-by: Patrice Chotard Reviewed-by: Patrick Delaunay --- drivers/serial/serial_stm32.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/serial/serial_stm32.c b/drivers/serial/serial_stm32.c index 93f70947ee..0085113f67 100644 --- a/drivers/serial/serial_stm32.c +++ b/drivers/serial/serial_stm32.c @@ -29,6 +29,10 @@ static void _stm32_serial_setbrg(fdt_addr_t base, { bool stm32f4 = uart_info->stm32f4; u32 int_div, mantissa, fraction, oversampling; + u8 uart_enable_bit = uart_info->uart_enable_bit; + + /* BRR register must be set when uart is disabled */ + clrbits_le32(base + CR1_OFFSET(stm32f4), BIT(uart_enable_bit)); int_div = DIV_ROUND_CLOSEST(clock_rate, baudrate); @@ -44,6 +48,8 @@ static void _stm32_serial_setbrg(fdt_addr_t base, fraction = int_div % oversampling; writel(mantissa | fraction, base + BRR_OFFSET(stm32f4)); + + setbits_le32(base + CR1_OFFSET(stm32f4), BIT(uart_enable_bit)); } static int stm32_serial_setbrg(struct udevice *dev, int baudrate) -- 2.39.5