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serial: stm32: fix rx data length when parity enabled

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- 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: 3489187204 ("serial: stm32: adding dma support")
Signed-off-by: Erwan Le Ray <erwan.leray@st.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Erwan Le Ray 2019-05-21 17:45:43 +02:00 committed by Greg Kroah-Hartman
parent 4f01d833fd
commit 6c5962f30b
2 changed files with 9 additions and 4 deletions
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12
drivers/tty/serial/stm32-usart.c
View File

@ -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++;

1
drivers/tty/serial/stm32-usart.h
View File

@ -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];