linux-kernel - [PATCH v2 2/6] atmel_serial: Use cpu

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Message-Id: <1198077130-9021-3-git-send-email-hskinnemoen@atmel.com>
Date:	Wed, 19 Dec 2007 16:12:06 +0100
From:	Haavard Skinnemoen <hskinnemoen@...el.com>
To:	Andrew Victor <linux@...im.org.za>
Cc:	Remy Bohmer <linux@...mer.net>,
	linux-arm-kernel@...ts.arm.linux.org.uk,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org, kernel@...32linux.org,
	Haavard Skinnemoen <hskinnemoen@...el.com>
Subject: [PATCH v2 2/6] atmel_serial: Use cpu_relax() when busy-waiting

Replace two instances of barrier() with cpu_relax() since that's the
right thing to do when busy-waiting. This does not actually change
anything since cpu_relax() is defined as barrier() on both ARM and
AVR32.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@...el.com>
---
 drivers/serial/atmel_serial.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index bd41529..61d71b0 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -623,7 +623,7 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
 	imr = UART_GET_IMR(port);
 	UART_PUT_IDR(port, -1);
 	while (!(UART_GET_CSR(port) & ATMEL_US_TXEMPTY))
-		barrier();
+		cpu_relax();
 
 	/* disable receiver and transmitter */
 	UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
@@ -802,7 +802,7 @@ void __init atmel_register_uart_fns(struct atmel_port_fns *fns)
 static void atmel_console_putchar(struct uart_port *port, int ch)
 {
 	while (!(UART_GET_CSR(port) & ATMEL_US_TXRDY))
-		barrier();
+		cpu_relax();
 	UART_PUT_CHAR(port, ch);
 }
 
-- 
1.5.3.4

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