serial: stm32: prevent TDR register overwrite when sending x_char
authorValentin Caron <valentin.caron@foss.st.com>
Tue, 11 Jan 2022 16:44:40 +0000 (17:44 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 26 Jan 2022 13:52:44 +0000 (14:52 +0100)
commitd3d079bde07e1b7deaeb57506dc0b86010121d17
treed8dc75df0226186049947b5a38bccb77bd85cd00
parent8838b2af23caf1ff0610caef2795d6668a013b2d
serial: stm32: prevent TDR register overwrite when sending x_char

When sending x_char in stm32_usart_transmit_chars(), driver can overwrite
the value of TDR register by the value of x_char. If this happens, the
previous value that was present in TDR register will not be sent through
uart.

This code checks if the previous value in TDR register is sent before
writing the x_char value into register.

Fixes: 48a6092fb41f ("serial: stm32-usart: Add STM32 USART Driver")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Valentin Caron <valentin.caron@foss.st.com>
Link: https://lore.kernel.org/r/20220111164441.6178-2-valentin.caron@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/stm32-usart.c