From a5f18286083fe450d6080abc8d4341c630f682dd Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= Date: Wed, 13 Dec 2023 18:43:12 +0100 Subject: [PATCH] serial: 8250-fsl: Only do the break workaround if IIR signals RLSI MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It can happen that while a break is received the transmitter gets empty and IIR signals a Transmitter holding register empty (THRI) event. In this case it's too early for the break workaround. Still doing it then results in the THRI event not being rereported which makes the driver miss that and e.g. for RS485 half-duplex communication it fails to switch back to RX mode. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20231213174312.2341013-1-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_fsl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c index 5cf675eadefe..b4ed442082a8 100644 --- a/drivers/tty/serial/8250/8250_fsl.c +++ b/drivers/tty/serial/8250/8250_fsl.c @@ -51,7 +51,8 @@ int fsl8250_handle_irq(struct uart_port *port) * immediately and interrupt the CPU again. The hardware clears LSR.BI * when the next valid char is read.) */ - if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) { + if (unlikely((iir & UART_IIR_ID) == UART_IIR_RLSI && + (up->lsr_saved_flags & UART_LSR_BI))) { up->lsr_saved_flags &= ~UART_LSR_BI; port->serial_in(port, UART_RX); uart_port_unlock_irqrestore(&up->port, flags);