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@atmel.com>
Acked-by: Andrew Victor <linux@maxim.org.za>
Tested-by: Marc Pignat <marc.pignat@hevs.ch>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index bb9c357..4d1ccc2 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -615,7 +615,7 @@
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);
@@ -794,7 +794,7 @@
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);
}