From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alan Cox Subject: [PATCH 08/30] Use barrier instead of cpu_relax for early blackfin boot Date: Tue, 24 Mar 2009 14:03:07 +0000 Message-ID: <20090324140257.12735.75468.stgit@localhost.localdomain> References: <20090324135930.12735.7827.stgit@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:48944 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755195AbZCXOCr (ORCPT ); Tue, 24 Mar 2009 10:02:47 -0400 In-Reply-To: <20090324135930.12735.7827.stgit@localhost.localdomain> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, torvalds@linux-foundation.org From: Graf Yang 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 Signed-off-by: Bryan Wu Signed-off-by: Alan Cox --- 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 318d69d..d46d764 100644 --- a/drivers/serial/bfin_5xx.c +++ b/drivers/serial/bfin_5xx.c @@ -1128,7 +1128,8 @@ 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); }