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| author | Marek Vasut <marex@denx.de> | 2023-02-23 05:22:52 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-03-09 17:16:11 +0100 |
| commit | c47527cbcc3c50800f34b8c684f29721f75de246 (patch) | |
| tree | 510c9fe502f2222c31f6931304fb9530e4404ef9 /drivers/tty/serial/stm32-usart.c | |
| parent | b4fd0afaa07f9f46c733e7cf17e4b4cb45461c3c (diff) | |
| download | linux-c47527cbcc3c50800f34b8c684f29721f75de246.tar.gz linux-c47527cbcc3c50800f34b8c684f29721f75de246.tar.bz2 linux-c47527cbcc3c50800f34b8c684f29721f75de246.zip | |
serial: stm32: Re-assert RTS/DE GPIO in RS485 mode only if more data are transmitted
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>
Diffstat (limited to 'drivers/tty/serial/stm32-usart.c')
| -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 bf51e2152dd5..1e38fc9b10c1 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -693,8 +693,9 @@ 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); } |