serial: 8250_early: confirm empty transmitter after sending characters

The current code waits until the transmitter becomes empty,
before sending each character, and after finishing the whole string.
This seems a bit redundant.

It can be more efficient by checking the transmitter only after sending
each character.  This should be safe because the transmitter is already
empty at the first entry of serial_putc().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 5afc4d440304428d9c0d26ffa7b2dbb12e92a9d8..20ec27bf138030a4482f95d552976e4a034987f9 100644 (file)
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -87,8 +87,8 @@ static void __init wait_for_xmitr(struct uart_port *port)
 
 static void __init serial_putc(struct uart_port *port, int c)
 {
-       wait_for_xmitr(port);
        serial8250_early_out(port, UART_TX, c);
+       wait_for_xmitr(port);
 }
 
 static void __init early_serial8250_write(struct console *console,
@@ -98,9 +98,6 @@ static void __init early_serial8250_write(struct console *console,
        struct uart_port *port = &device->port;
 
        uart_console_write(port, s, count, serial_putc);
-
-       /* Wait for transmitter to become empty */
-       wait_for_xmitr(port);
 }
 
 static void __init init_port(struct earlycon_device *device)