[PATCH 02/18] Blackfin Serial Driver: use barrier instead of cpu_relax for Blackfin SMP like patch

[Bryan Wu]

From: Graf Yang <graf.yang@xxxxxxxxxx>

We are making a SMP like patch to blackfin, cpu_relax() is replaced by a
data cache flush function which will count it to a per-cpu counter.
If this serial function is called too early, the per-cpu data area have
not been initialized, this call will cause crash.
So we'd like to use barrier() instead of cpu_relax().

Signed-off-by: Graf Yang <graf.yang@xxxxxxxxxx>
Signed-off-by: Bryan Wu <cooloney@xxxxxxxxxx>
---
 drivers/serial/bfin_5xx.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 52ccc27..350bfc4 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -1129,7 +1129,8 @@ static __init void early_serial_putc(struct uart_port *port, int ch)
 	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
 
 	while ((!(UART_GET_LSR(uart) & THRE)) && --timeout)
-		cpu_relax();
+		barrier();
+
 	UART_PUT_CHAR(uart, ch);
 }
 
-- 
1.5.6.3
--
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/