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serial: apbuart: fix console prompt on qemu

Message ID 20231226121607.GA2622970@ravnborg.org
State New
Headers show
Series serial: apbuart: fix console prompt on qemu | expand

Commit Message

Sam Ravnborg Dec. 26, 2023, 12:16 p.m. UTC 
When using a leon kernel with qemu there where no console prompt.
The root cause is the handling of the fifo size in the tx part of the
apbuart driver.

The qemu uart driver only have a very rudimentary status handling and do
not report the number of chars queued in the tx fifo in the status register.
So the driver ends up with a fifo size of 1.

In the tx path the fifo size is divided by 2 - resulting in a fifo
size of zero.

The original implementation would always try to send one char, but
after the introduction of uart_port_tx_limited() the fifo size is
respected even for the first char.

There seems to be no good reason to divide the fifo size with two - so
remove this. It looks like something copied from the original amba driver.

With qemu we now have a minimum fifo size of one char, so we show
the prompt.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Fixes: d11cc8c3c4b6 ("tty: serial: use uart_port_tx_limited()")
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: linux-serial@vger.kernel.org
Cc: sparclinux@vger.kernel.org
---
 drivers/tty/serial/apbuart.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/tty/serial/apbuart.c b/drivers/tty/serial/apbuart.c
index 716cb014c028..364599f256db 100644
--- a/drivers/tty/serial/apbuart.c
+++ b/drivers/tty/serial/apbuart.c
@@ -122,7 +122,7 @@  static void apbuart_tx_chars(struct uart_port *port)
 {
 	u8 ch;
 
-	uart_port_tx_limited(port, ch, port->fifosize >> 1,
+	uart_port_tx_limited(port, ch, port->fifosize,
 		true,
 		UART_PUT_CHAR(port, ch),
 		({}));