From: Erwan Le Ray erwan.leray@st.com
[ Upstream commit 6c5962f30bce147b1c83869085f3ddde3b34c9e3 ]
- Fixes a rx data error when data length < 8 bits and parity is enabled. RDR register MSB is used for parity bit reception. - Adds a mask to ignore MSB when data is get from RDR.
Fixes: 3489187204eb ("serial: stm32: adding dma support") Signed-off-by: Erwan Le Ray erwan.leray@st.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/serial/stm32-usart.c | 12 ++++++++---- drivers/tty/serial/stm32-usart.h | 1 + 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index f6b739351ddec..0a7953e5ce47a 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -194,8 +194,8 @@ static int stm32_pending_rx(struct uart_port *port, u32 *sr, int *last_res, return 0; }
-static unsigned long -stm32_get_char(struct uart_port *port, u32 *sr, int *last_res) +static unsigned long stm32_get_char(struct uart_port *port, u32 *sr, + int *last_res) { struct stm32_port *stm32_port = to_stm32_port(port); struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; @@ -205,10 +205,13 @@ stm32_get_char(struct uart_port *port, u32 *sr, int *last_res) c = stm32_port->rx_buf[RX_BUF_L - (*last_res)--]; if ((*last_res) == 0) *last_res = RX_BUF_L; - return c; } else { - return readl_relaxed(port->membase + ofs->rdr); + c = readl_relaxed(port->membase + ofs->rdr); + /* apply RDR data mask */ + c &= stm32_port->rdr_mask; } + + return c; }
static void stm32_receive_chars(struct uart_port *port, bool threaded) @@ -679,6 +682,7 @@ static void stm32_set_termios(struct uart_port *port, struct ktermios *termios, cr2 |= USART_CR2_STOP_2B;
bits = stm32_get_databits(termios); + stm32_port->rdr_mask = (BIT(bits) - 1);
if (cflag & PARENB) { bits++; diff --git a/drivers/tty/serial/stm32-usart.h b/drivers/tty/serial/stm32-usart.h index 8d34802e572ed..30d2433e27c3c 100644 --- a/drivers/tty/serial/stm32-usart.h +++ b/drivers/tty/serial/stm32-usart.h @@ -254,6 +254,7 @@ struct stm32_port { bool hw_flow_control; bool fifoen; int wakeirq; + int rdr_mask; /* receive data register mask */ };
static struct stm32_port stm32_ports[STM32_MAX_PORTS];