[PATCH v2 1/3] serial: 8250_early: optimize early 8250 uart
From: Vineet Gupta
Date: Mon Jan 05 2015 - 06:31:12 EST
In early 8250, IER is already zero so no point in writing this - twice
per char.
This helped improve the SystemC model based ARC OSCI platform
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxx>
Cc: linux-serial@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: Rob Herring <robh@xxxxxxxxxx>
---
drivers/tty/serial/8250/8250_early.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 4858b8a99d3b..ce2a8abd1f54 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -95,13 +95,16 @@ static void __init early_serial8250_write(struct console *console,
/* Save the IER and disable interrupts */
ier = serial8250_early_in(port, UART_IER);
- serial8250_early_out(port, UART_IER, 0);
+ if (ier)
+ serial8250_early_out(port, UART_IER, 0);
uart_console_write(port, s, count, serial_putc);
/* Wait for transmitter to become empty and restore the IER */
wait_for_xmitr(port);
- serial8250_early_out(port, UART_IER, ier);
+
+ if (ier)
+ serial8250_early_out(port, UART_IER, ier);
}
static unsigned int __init probe_baud(struct uart_port *port)
--
1.9.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/