Messages in this thread Patch in this message | | | From | Vineet Gupta <> | Subject | [PATCH 1/3] serial: 8250_early: optimize early 8250 uart | Date | Wed, 24 Dec 2014 12:42:14 +0530 |
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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@synopsys.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jiri Slaby <jslaby@suse.cz> Cc: linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Rob Herring <robh@kernel.org> --- 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) -- 1.8.3.2
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