From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vineet Gupta Subject: [PATCH v2 1/3] serial: 8250_early: optimize early 8250 uart Date: Mon, 5 Jan 2015 17:00:35 +0530 Message-ID: <1420457437-17636-2-git-send-email-vgupta@synopsys.com> References: <1420457437-17636-1-git-send-email-vgupta@synopsys.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <1420457437-17636-1-git-send-email-vgupta@synopsys.com> Sender: linux-kernel-owner@vger.kernel.org To: gregkh@linuxfoundation.org Cc: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, robh@kernel.org, jslaby@suse.cz, Vineet Gupta List-Id: linux-serial@vger.kernel.org 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 Cc: Greg Kroah-Hartman Cc: Jiri Slaby Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Rob Herring --- 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