diff options
| author | Marek Vasut <marex@denx.de> | 2023-02-23 05:22:52 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-11 23:03:27 +0900 |
| commit | c996ca87cf68e5ffa34f1c0f3657463bf07da03a (patch) | |
| tree | db69b324b2549270f7749b1d9377dfba4417d65b /drivers | |
| parent | 3c5fafc27c02ff8a3a71fa4b0db2444e6f9d94c1 (diff) | |
| download | linux-c996ca87cf68e5ffa34f1c0f3657463bf07da03a.tar.gz | |
serial: stm32: Re-assert RTS/DE GPIO in RS485 mode only if more data are transmitted
[ Upstream commit c47527cbcc3c50800f34b8c684f29721f75de246 ]
The stm32_usart_transmit_chars() may be called with empty or stopped
transmit queue, and no XON/OFF character pending. This can happen at
the end of transmission, where this last call is used to either handle
the XON/XOFF x_char, or disable TX interrupt if queue is empty or
stopped.
If that occurs, do not assert the RS485 RTS/DE GPIO anymore, as the
GPIO would remain asserted past the end of transmission and that would
block the RS485 bus after the transmission.
Only assert the RS485 RTS/DE GPIO if there is either pending XON/XOFF
x_char, or at least one character in running transmit queue.
Fixes: d7c76716169d ("serial: stm32: Use TC interrupt to deassert GPIO RTS in RS485 mode")
Signed-off-by: Marek Vasut <marex@denx.de>
Link: https://lore.kernel.org/r/20230223042252.95480-2-marex@denx.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/stm32-usart.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 0e6ef24419c8..28edbaf7bb32 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -690,8 +690,9 @@ static void stm32_usart_transmit_chars(struct uart_port *port) int ret; if (!stm32_port->hw_flow_control && - port->rs485.flags & SER_RS485_ENABLED) { - stm32_port->txdone = false; + port->rs485.flags & SER_RS485_ENABLED && + (port->x_char || + !(uart_circ_empty(xmit) || uart_tx_stopped(port)))) { stm32_usart_tc_interrupt_disable(port); stm32_usart_rs485_rts_enable(port); } |