Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758247AbZCXOGk (ORCPT ); Tue, 24 Mar 2009 10:06:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758089AbZCXOC5 (ORCPT ); Tue, 24 Mar 2009 10:02:57 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:48946 "EHLO www.etchedpixels.co.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758075AbZCXOCy (ORCPT ); Tue, 24 Mar 2009 10:02:54 -0400 From: Alan Cox Subject: [PATCH 09/30] blackfin: Explain why we cannot cpu_relax() in early serial code To: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, torvalds@linux-foundation.org Date: Tue, 24 Mar 2009 14:03:16 +0000 Message-ID: <20090324140313.12735.24344.stgit@localhost.localdomain> In-Reply-To: <20090324135930.12735.7827.stgit@localhost.localdomain> References: <20090324135930.12735.7827.stgit@localhost.localdomain> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1139 Lines: 32 From: Mike Frysinger Signed-off-by: Mike Frysinger Signed-off-by: Bryan Wu Signed-off-by: Alan Cox --- drivers/serial/bfin_5xx.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c index d46d764..c7c0c1b 100644 --- a/drivers/serial/bfin_5xx.c +++ b/drivers/serial/bfin_5xx.c @@ -1127,6 +1127,10 @@ static __init void early_serial_putc(struct uart_port *port, int ch) unsigned timeout = 0xffff; struct bfin_serial_port *uart = (struct bfin_serial_port *)port; + /* We cannot cpu_relax() here as doing so on the BF561 relies + * on the per-cpu region being setup, and since this is early + * serial code, it may not yet be usable ... + */ while ((!(UART_GET_LSR(uart) & THRE)) && --timeout) barrier(); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/